DIAGNOSIS A bad or buggy firmware update can sometimes cause performance issues or compatibility problems with certain devices.
FIX The first step is a full system reboot to clear any glitches. Don't just restart from the app. 1) Unplug the power from all your XT8 nodes and your modem. 2) Wait two minutes. 3) Plug in and turn on the modem, wait for its lights to stabilize. 4) Plug in the main router node, wait for solid white light. 5) Then plug in your satellite nodes one by one. Test again before rolling back.
IF THAT DIDN'T WORK You can manually revert to an older firmware. Go to the ASUS support site, find your XT8 model, and download the previous firmware version file (.trx). In the router web interface, go to Administration > Firmware Upgrade. Click "Upload" and select the older file you downloaded. The system will do the rest. This process takes a few minutes and will reboot your network.
HEADS UP Rolling back firmware will reset all your custom settings (like port forwarding, DHCP reservations) to the defaults of that older version. Be prepared to reconfigure your network afterward. It's a good idea to back up your settings before any update in the future.