@Brh1 

Thanks for reaching out. I understand that after a recent internet outage, your Deco Mesh guest network is visible but devices cannot connect to it—they either fail to obtain an IP address or cannot reconnect, while the IoT network works fine. You've already tried power cycling the Deco units, but the issue persists.

Here are some troubleshooting steps to help resolve the issue with your guest network:

1. Double-check Guest Network Settings:
• Open the Deco app and go to MORE > Wi-Fi settings or Guest Network.
• Ensure the guest network is enabled, visible (not hidden), and the password is correct (no extra spaces or special characters).

2. Reboot the Main Deco:
• Power cycle the main Deco unit again. Sometimes a second reboot can help clear network glitches.

3. Check for Device Blocking:
• In the Deco app, go to MORE > Access Control (Allow List or Block List) and make sure none of your devices are accidentally blocked from the guest network.

4. Update Firmware:
• Make sure all Deco units are running the same firmware version. You mentioned one Deco has a different firmware. Please update all units to the latest version to avoid compatibility issues. You can check and update firmware via the Deco app or at http://tplinkdeco.net > Advanced > Upgrade Firmware.

5. Encryption Settings:
• In the Deco app, go to MORE > Wi-Fi settings or Guest Network and try changing the encryption method to WPA2/WPA-PSK or "none". Some devices may have trouble connecting if the encryption type is not compatible.

6. Fast Roaming:
• Go to MORE > Advanced > Fast Roaming in the Deco app and disable this feature. Some devices, especially on guest or IoT networks, may have trouble connecting if Fast Roaming is enabled.

7. Remove Device from Offline List:
• In the Deco app, check the Client List (offline clients). If your device appears there, delete it to reset its connection preferences.

8. Test with Another Device:
• Try connecting a different device to the guest network to see if the problem is device-specific.

9. Compare with Main Network:
• If devices can connect to the main or IoT network but not the guest network, this further points to a guest network configuration or firmware issue.

If you continue to have issues after these steps, please contact TP-Link Support and provide details of the troubleshooting you've completed.

For more information, you can also refer to our detailed FAQ: https://www.tp-link.com/support/faq/2718/

  @Brh1 

So no cable guest network is up? Add Ethernet cable guest network is down?

  @Brh1 

Are you using a network switch? If so Can i please have the name of the switch and the model number. 

  @Brh1 

Model number? If your switch is whats know as a managed switch this could be why your having this issue but need the model number so see if the switch is managed vs unmanaged 

  @Brh1 

Ok beside maybe it being a bad cable not sure what else is causing this lets get you over to one of the senior engineers 

First please access the Deco web UI by entering "tplinkdeco.net" in your browser. Navigate to Advanced > System > System Log, select "ALL" in the log type, and save the file to your local computer. Then follow the steps below making sure to attach the logs to the email.

I recommend sending an email to forumsupport.usa@tp-link.com with the following information:

Subject: [Forum Escalation][ID 846742] Firmware update and now guest network failing

Forum Nickname: [User Provided]

Thread URL: https://community.tp-link.com/us/home/forum/topic/846742

Model&Version: [User Provided]

Description: [User Provided]

Any Other Relevant Information (Logs, Config Files, Images, etc.): [User Provided]

 In the template above please fill in the areas that say [User Provided].  This will open a case with our engineering team, and they will work with you via email.