I've got 2x ZenWiFi XT8 (RT-AX95Q) connected with ethernet backhaul running in AP mode (they are out of wifi range of each other).
Installed the firmware first on to the primary node. It rebooted and the connectivity was working fine. The sole noted issue was that
only existing wifi clients seemed to be allowed to connect, anything new wasn't working. The http service was down and I couldn't start httpd - received error "3069733712:error:0B080074:lib(11):func(128):reason(116):NA:0:". This meant no way to get to the GUI for config
The secondary node was then stuck in a limbo whereby you couldn't connect to the GUI to update it. At this point with the firmwares out of sync, wifi was being repeated correctly on the secondary node. To get out of this dead end I did a factory reset on both and upgraded both to the very latest beta firmware. I then factory reset both again. After configuring everything there were a few issues still:
1. Guest network didn't work on primary node - could connect but wasn't getting an IP from my modem which is the DHCP server. Didn't test guest on secondary node.
2. Normal wifi on the secondary guest was transmitting, but again, no IP being given and there was no connectivity to the network.
I see some people have had similar sounding issues with their XT8 but others seem to have had no issues. Personally I wouldn't recommend anyone with an XT8 and a similar config to the above trying this firmware quite yet as resetting and installing firmwares can be a real time burglar.