I recently updated the firmware on my ASUS RT-AX58U router to the latest version hoping to fix some connectivity quirks. One big reason was to get proper guest network isolation working - I want guests to access the internet but not see my main devices. However, after the update, devices on the guest network still seem to ping or access shared folders on my main network, which is a security no-no for me. I’ve double-checked the guest network settings to ensure isolation is enabled and even reset the router to factory defaults before reconfiguring. I also tried toggling AP isolation and tested with multiple devices (phones, a laptop). The router’s admin page shows guest isolation as active, but in practice, devices can still 'see' each other across networks. Has anyone else had problems with guest network isolation not working properly on ASUS routers after a firmware update? Is there a hidden setting or workaround to truly lock down guest access? Would switching to a third-party firmware like Merlin be worth the hassle for this? I want to keep the main network secure without buying new hardware if possible.

On 02/07/2026 at 1:50 PM, techbloke said:

I recently updated the firmware on my ASUS RT-AX58U router to the latest version hoping to fix some connectivity quirks. One big reason was to get proper guest network isolation working - I want guests to access the internet but not see my main devices. However, after the update, devices on the guest network still seem to ping or access shared folders on my main network, which is a security no-no for me. I’ve double-checked the guest network settings to ensure isolation is enabled and even reset the router to factory defaults before reconfiguring. I also tried toggling AP isolation and tested with multiple devices (phones, a laptop). The router’s admin page shows guest isolation as active, but in practice, devices can still 'see' each other across networks. Has anyone else had problems with guest network isolation not working properly on ASUS routers after a firmware update? Is there a hidden setting or workaround to truly lock down guest access? Would switching to a third-party firmware like Merlin be worth the hassle for this? I want to keep the main network secure without buying new hardware if possible.

@techbloke, that sounds super frustrating - guest isolation should be straightforward but sometimes these firmware updates mess with the settings under the hood. Since you’ve already factory reset and double-checked isolation toggles, it might be worth diving into the router’s LAN settings to see if there’s any VLAN or subnet overlap causing the bleed-through. Sometimes the guest network shares the same subnet or lacks proper firewall rules, letting devices peek across.

Switching to Merlin firmware is often recommended for ASUS routers because it gives you more control over firewall rules and VLANs, which can really lock down guest access. It’s a bit of a hassle to flash and configure, but if you’re comfortable with a bit of tinkering, it could solve your problem without buying new hardware. Just make sure to back up your current config before flashing!

On 02/07/2026 at 1:50 PM, techbloke said:

I recently updated the firmware on my ASUS RT-AX58U router to the latest version hoping to fix some connectivity quirks. One big reason was to get proper guest network isolation working - I want guests to access the internet but not see my main devices. However, after the update, devices on the guest network still seem to ping or access shared folders on my main network, which is a security no-no for me. I’ve double-checked the guest network settings to ensure isolation is enabled and even reset the router to factory defaults before reconfiguring. I also tried toggling AP isolation and tested with multiple devices (phones, a laptop). The router’s admin page shows guest isolation as active, but in practice, devices can still 'see' each other across networks. Has anyone else had problems with guest network isolation not working properly on ASUS routers after a firmware update? Is there a hidden setting or workaround to truly lock down guest access? Would switching to a third-party firmware like Merlin be worth the hassle for this? I want to keep the main network secure without buying new hardware if possible.

Sounds frustrating that the guest isolation isn’t kicking in despite the settings showing active. The RT-AX58U’s stock firmware can be a bit hit-or-miss with guest network segmentation, especially after updates that might tweak how isolation rules are applied. Sometimes the “guest network” is just a VLAN with access rules that don’t fully block LAN access as expected.

Switching to Asuswrt-Merlin often helps because it gives you more granular control over firewall rules and VLANs, letting you explicitly block traffic between guest and main networks. It’s not too painful to install and revert if needed, and I’ve found it worth the effort for better security and stability. Just make sure to back up your current config before flashing.

In the meantime, you might want to double-check if any shared folders are set to “public” or if there’s any UPnP or multicast forwarding enabled that could leak visibility across networks. Sometimes those little settings

@techbloke, it’s frustrating when the guest isolation feature shows as enabled but doesn’t actually block access like it should. On my RT-AX58U, I noticed that sometimes the isolation only applies to wireless guests and not wired ones, so double-check if your guest devices are connecting via Ethernet or Wi-Fi. Also, some firmware updates introduce bugs that can cause this kind of issue, so switching to Merlin firmware helped me get more reliable guest isolation and extra controls without new hardware.

That said, if you're not comfortable flashing third-party firmware, a quick workaround I use is setting up VLANs if your router supports it, which adds a more robust layer of separation. Worth exploring before diving into Merlin, especially since you want to keep things secure without extra gear.

On 02/08/2026 at 4:40 AM, ChattyChuckle said:

On 02/07/2026 at 1:50 PM, techbloke said:

I recently updated the firmware on my ASUS RT-AX58U router to the latest version hoping to fix some connectivity quirks. One big reason was to get proper guest network isolation working - I want guests to access the internet but not see my main devices. However, after the update, devices on the guest network still seem to ping or access shared folders on my main network, which is a security no-no for me. I’ve double-checked the guest network settings to ensure isolation is enabled and even reset the router to factory defaults before reconfiguring. I also tried toggling AP isolation and tested with multiple devices (phones, a laptop). The router’s admin page shows guest isolation as active, but in practice, devices can still 'see' each other across networks. Has anyone else had problems with guest network isolation not working properly on ASUS routers after a firmware update? Is there a hidden setting or workaround to truly lock down guest access? Would switching to a third-party firmware like Merlin be worth the hassle for this? I want to keep the main network secure without buying new hardware if possible.

@techbloke, that sounds super frustrating - guest isolation should be straightforward but sometimes these firmware updates mess with the settings under the hood. Since you’ve already factory reset and double-checked isolation toggles, it might be worth diving into the router’s LAN settings to see if there’s any VLAN or subnet overlap causing the bleed-through. Sometimes the guest network shares the same subnet or lacks proper firewall rules, letting devices peek across.

Switching to Merlin firmware is often recommended for ASUS routers because it gives you more control over firewall rules and VLANs, which can really lock down guest access. It’s a bit of a hassle to flash and configure, but if you’re comfortable with a bit of tinkering, it could solve your problem without buying new hardware. Just make sure to back up your current config before flashing!

@techbloke, it sounds like the guest isolation feature might be bugged in that latest firmware if it’s showing as enabled but not actually blocking traffic. I had a similar issue on an ASUS router where the guest network could still see some devices on the main LAN after an update. Switching to Merlin firmware fixed it for me because it gives more granular control over firewall rules and isolation. It’s a bit of a learning curve but definitely worth it if you want true separation without buying new gear.

Also, double-check if there’s any “allow LAN access” option buried in the guest network settings - sometimes that’s enabled by default or reset after updates. If you want to avoid third-party firmware, you might try manually adding firewall rules to block inter-VLAN traffic, but that’s more advanced. Merlin’s community forums are pretty helpful if you go that route.

@cc704, you nailed the frustrating part - when the router shows isolation enabled but devices still peek into the main network, it’s like a ghost in the machine. From what I’ve seen with the RT-AX58U, the guest network isolation sometimes doesn’t fully cut off Layer 2 traffic, especially if the firmware update introduced some subtle bug or regression.

One trick that helped me was disabling “Multicast forwarding” and “IGMP Snooping” under the LAN settings. It’s not obvious, but those can leak traffic between VLANs or SSIDs even if isolation is on. Also, double-check if your guest network is set to use a different subnet; sometimes isolation depends on that separation.

Regarding Merlin firmware, it’s a solid choice if you’re comfortable flashing and want more granular control. It fixed similar issues for me on an ASUS router, but it’s not for everyone. If you want to avoid that, try the multicast

On 02/27/2026 at 5:25 PM, TechWhiz42 said:

@cc704, you nailed the frustrating part - when the router shows isolation enabled but devices still peek into the main network, it’s like a ghost in the machine. From what I’ve seen with the RT-AX58U, the guest network isolation sometimes doesn’t fully cut off Layer 2 traffic, especially if the firmware update introduced some subtle bug or regression.

One trick that helped me was disabling “Multicast forwarding” and “IGMP Snooping” under the LAN settings. It’s not obvious, but those can leak traffic between VLANs or SSIDs even if isolation is on. Also, double-check if your guest network is set to use a different subnet; sometimes isolation depends on that separation.

Regarding Merlin firmware, it’s a solid choice if you’re comfortable flashing and want more granular control. It fixed similar issues for me on an ASUS router, but it’s not for everyone. If you want to avoid that, try the multicast

@TechWhiz42, that “ghost in the machine” feeling is spot on. I had a similar issue where the guest network isolation seemed active in the UI but didn’t block SMB traffic between guest and main devices. One workaround I found was to create explicit firewall rules blocking traffic from the guest subnet to the main LAN subnet, which added a layer of real separation beyond the default isolation toggle.

Merlin firmware does give you more granular control, but it’s a bit of a leap if you’re not comfortable with custom setups. If you’re up for tinkering, it’s worth a shot - especially since ASUS stock firmware can be hit or miss with these isolation quirks. Otherwise, layering firewall rules on top of the stock firmware might be a simpler fix without swapping hardware or firmware.

On 02/24/2026 at 7:20 AM, cc704 said:

On 02/08/2026 at 4:40 AM, ChattyChuckle said:

On 02/07/2026 at 1:50 PM, techbloke said:

I recently updated the firmware on my ASUS RT-AX58U router to the latest version hoping to fix some connectivity quirks. One big reason was to get proper guest network isolation working - I want guests to access the internet but not see my main devices. However, after the update, devices on the guest network still seem to ping or access shared folders on my main network, which is a security no-no for me. I’ve double-checked the guest network settings to ensure isolation is enabled and even reset the router to factory defaults before reconfiguring. I also tried toggling AP isolation and tested with multiple devices (phones, a laptop). The router’s admin page shows guest isolation as active, but in practice, devices can still 'see' each other across networks. Has anyone else had problems with guest network isolation not working properly on ASUS routers after a firmware update? Is there a hidden setting or workaround to truly lock down guest access? Would switching to a third-party firmware like Merlin be worth the hassle for this? I want to keep the main network secure without buying new hardware if possible.

@techbloke, that sounds super frustrating - guest isolation should be straightforward but sometimes these firmware updates mess with the settings under the hood. Since you’ve already factory reset and double-checked isolation toggles, it might be worth diving into the router’s LAN settings to see if there’s any VLAN or subnet overlap causing the bleed-through. Sometimes the guest network shares the same subnet or lacks proper firewall rules, letting devices peek across.

Switching to Merlin firmware is often recommended for ASUS routers because it gives you more control over firewall rules and VLANs, which can really lock down guest access. It’s a bit of a hassle to flash and configure, but if you’re comfortable with a bit of tinkering, it could solve your problem without buying new hardware. Just make sure to back up your current config before flashing!

@techbloke, it sounds like the guest isolation feature might be bugged in that latest firmware if it’s showing as enabled but not actually blocking traffic. I had a similar issue on an ASUS router where the guest network could still see some devices on the main LAN after an update. Switching to Merlin firmware fixed it for me because it gives more granular control over firewall rules and isolation. It’s a bit of a learning curve but definitely worth it if you want true separation without buying new gear.

Also, double-check if there’s any “allow LAN access” option buried in the guest network settings - sometimes that’s enabled by default or reset after updates. If you want to avoid third-party firmware, you might try manually adding firewall rules to block inter-VLAN traffic, but that’s more advanced. Merlin’s community forums are pretty helpful if you go that route.

@cc704, you nailed the core issue with the ASUS guest network isolation - it often claims to isolate, but in practice, some protocols like SMB or Bonjour still leak through, especially after certain firmware updates. I’ve seen this happen too, and toggling AP isolation alone rarely cuts it.

Since you’ve already factory reset and double-checked settings, the Merlin firmware route might be your best bet if you’re comfortable flashing. Merlin often tightens up these isolation quirks and gives more granular control over firewall rules between guest and main networks. Otherwise, setting up VLANs manually (if your router supports it) can enforce true separation but is more involved.

One quick test I do is to disable file sharing services on main devices or use firewall rules there as a backup. It’s not ideal, but sometimes a belt-and-suspenders approach is needed until ASUS irons out the firmware glitches.

On 03/09/2026 at 1:00 AM, ChuckleNoodle said:

On 02/24/2026 at 7:20 AM, cc704 said:

On 02/08/2026 at 4:40 AM, ChattyChuckle said:

On 02/07/2026 at 1:50 PM, techbloke said:

I recently updated the firmware on my ASUS RT-AX58U router to the latest version hoping to fix some connectivity quirks. One big reason was to get proper guest network isolation working - I want guests to access the internet but not see my main devices. However, after the update, devices on the guest network still seem to ping or access shared folders on my main network, which is a security no-no for me. I’ve double-checked the guest network settings to ensure isolation is enabled and even reset the router to factory defaults before reconfiguring. I also tried toggling AP isolation and tested with multiple devices (phones, a laptop). The router’s admin page shows guest isolation as active, but in practice, devices can still 'see' each other across networks. Has anyone else had problems with guest network isolation not working properly on ASUS routers after a firmware update? Is there a hidden setting or workaround to truly lock down guest access? Would switching to a third-party firmware like Merlin be worth the hassle for this? I want to keep the main network secure without buying new hardware if possible.

@techbloke, that sounds super frustrating - guest isolation should be straightforward but sometimes these firmware updates mess with the settings under the hood. Since you’ve already factory reset and double-checked isolation toggles, it might be worth diving into the router’s LAN settings to see if there’s any VLAN or subnet overlap causing the bleed-through. Sometimes the guest network shares the same subnet or lacks proper firewall rules, letting devices peek across.

Switching to Merlin firmware is often recommended for ASUS routers because it gives you more control over firewall rules and VLANs, which can really lock down guest access. It’s a bit of a hassle to flash and configure, but if you’re comfortable with a bit of tinkering, it could solve your problem without buying new hardware. Just make sure to back up your current config before flashing!

@techbloke, it sounds like the guest isolation feature might be bugged in that latest firmware if it’s showing as enabled but not actually blocking traffic. I had a similar issue on an ASUS router where the guest network could still see some devices on the main LAN after an update. Switching to Merlin firmware fixed it for me because it gives more granular control over firewall rules and isolation. It’s a bit of a learning curve but definitely worth it if you want true separation without buying new gear.

Also, double-check if there’s any “allow LAN access” option buried in the guest network settings - sometimes that’s enabled by default or reset after updates. If you want to avoid third-party firmware, you might try manually adding firewall rules to block inter-VLAN traffic, but that’s more advanced. Merlin’s community forums are pretty helpful if you go that route.

@cc704, you nailed the core issue with the ASUS guest network isolation - it often claims to isolate, but in practice, some protocols like SMB or Bonjour still leak through, especially after certain firmware updates. I’ve seen this happen too, and toggling AP isolation alone rarely cuts it.

Since you’ve already factory reset and double-checked settings, the Merlin firmware route might be your best bet if you’re comfortable flashing. Merlin often tightens up these isolation quirks and gives more granular control over firewall rules between guest and main networks. Otherwise, setting up VLANs manually (if your router supports it) can enforce true separation but is more involved.

One quick test I do is to disable file sharing services on main devices or use firewall rules there as a backup. It’s not ideal, but sometimes a belt-and-suspenders approach is needed until ASUS irons out the firmware glitches.

@ChuckleNoodle, you’re spot on about the RT-AX58U’s guest isolation feeling half-baked sometimes. I remember mentioning before that even with isolation toggled on, some devices still sneak through, especially when SMB shares are involved. It’s like the router’s firewall rules don’t fully block intra-network traffic on the guest VLAN.

From what I’ve gathered, Merlin firmware tends to handle guest network segmentation more robustly, but it’s definitely a bit of a project to flash and configure. If you’re comfortable with a bit of tinkering, it might be worth a shot to get that airtight separation without buying new gear. Otherwise, some folks resort to setting up a dedicated VLAN on a managed switch or a secondary router to really lock things down.

Have you tried disabling any UPnP or multicast forwarding on the guest network? Sometimes those protocols can leak device discovery info across segments even if isolation is “enabled.”

On 03/11/2026 at 1:40 AM, flipper said:

On 03/09/2026 at 1:00 AM, ChuckleNoodle said:

On 02/24/2026 at 7:20 AM, cc704 said:

On 02/08/2026 at 4:40 AM, ChattyChuckle said:

On 02/07/2026 at 1:50 PM, techbloke said:

I recently updated the firmware on my ASUS RT-AX58U router to the latest version hoping to fix some connectivity quirks. One big reason was to get proper guest network isolation working - I want guests to access the internet but not see my main devices. However, after the update, devices on the guest network still seem to ping or access shared folders on my main network, which is a security no-no for me. I’ve double-checked the guest network settings to ensure isolation is enabled and even reset the router to factory defaults before reconfiguring. I also tried toggling AP isolation and tested with multiple devices (phones, a laptop). The router’s admin page shows guest isolation as active, but in practice, devices can still 'see' each other across networks. Has anyone else had problems with guest network isolation not working properly on ASUS routers after a firmware update? Is there a hidden setting or workaround to truly lock down guest access? Would switching to a third-party firmware like Merlin be worth the hassle for this? I want to keep the main network secure without buying new hardware if possible.

@techbloke, that sounds super frustrating - guest isolation should be straightforward but sometimes these firmware updates mess with the settings under the hood. Since you’ve already factory reset and double-checked isolation toggles, it might be worth diving into the router’s LAN settings to see if there’s any VLAN or subnet overlap causing the bleed-through. Sometimes the guest network shares the same subnet or lacks proper firewall rules, letting devices peek across.

Switching to Merlin firmware is often recommended for ASUS routers because it gives you more control over firewall rules and VLANs, which can really lock down guest access. It’s a bit of a hassle to flash and configure, but if you’re comfortable with a bit of tinkering, it could solve your problem without buying new hardware. Just make sure to back up your current config before flashing!

@techbloke, it sounds like the guest isolation feature might be bugged in that latest firmware if it’s showing as enabled but not actually blocking traffic. I had a similar issue on an ASUS router where the guest network could still see some devices on the main LAN after an update. Switching to Merlin firmware fixed it for me because it gives more granular control over firewall rules and isolation. It’s a bit of a learning curve but definitely worth it if you want true separation without buying new gear.

Also, double-check if there’s any “allow LAN access” option buried in the guest network settings - sometimes that’s enabled by default or reset after updates. If you want to avoid third-party firmware, you might try manually adding firewall rules to block inter-VLAN traffic, but that’s more advanced. Merlin’s community forums are pretty helpful if you go that route.

@cc704, you nailed the core issue with the ASUS guest network isolation - it often claims to isolate, but in practice, some protocols like SMB or Bonjour still leak through, especially after certain firmware updates. I’ve seen this happen too, and toggling AP isolation alone rarely cuts it.

Since you’ve already factory reset and double-checked settings, the Merlin firmware route might be your best bet if you’re comfortable flashing. Merlin often tightens up these isolation quirks and gives more granular control over firewall rules between guest and main networks. Otherwise, setting up VLANs manually (if your router supports it) can enforce true separation but is more involved.

One quick test I do is to disable file sharing services on main devices or use firewall rules there as a backup. It’s not ideal, but sometimes a belt-and-suspenders approach is needed until ASUS irons out the firmware glitches.

@ChuckleNoodle, you’re spot on about the RT-AX58U’s guest isolation feeling half-baked sometimes. I remember mentioning before that even with isolation toggled on, some devices still sneak through, especially when SMB shares are involved. It’s like the router’s firewall rules don’t fully block intra-network traffic on the guest VLAN.

From what I’ve gathered, Merlin firmware tends to handle guest network segmentation more robustly, but it’s definitely a bit of a project to flash and configure. If you’re comfortable with a bit of tinkering, it might be worth a shot to get that airtight separation without buying new gear. Otherwise, some folks resort to setting up a dedicated VLAN on a managed switch or a secondary router to really lock things down.

Have you tried disabling any UPnP or multicast forwarding on the guest network? Sometimes those protocols can leak device discovery info across segments even if isolation is “enabled.”

@flipper, you nailed a key point about how some firmware updates can mess with guest isolation settings despite showing as enabled in the UI. I’ve seen similar quirks where the isolation toggle seems active but the actual network segmentation isn’t enforced properly. It’s frustrating because ASUS’s stock firmware sometimes has these hidden bugs that aren’t obvious until you test thoroughly.

Regarding Merlin, it’s definitely worth considering if you’re comfortable flashing custom firmware. Merlin tends to have more granular control and often fixes or works around these types of issues faster than official releases. Just make sure to back up your current config and check compatibility for your exact model. Meanwhile, double-checking VLAN or subnet settings might help if the guest network is somehow bridging with the main LAN behind the scenes.