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...
@meekgeek1 there are a number of niggles with the XT8 and I assume these are present on the CT8. Still no resolution on the fact that the guest network can only be on the main hub. Secondly as a system it doesn't really hand together quite right - for example on my second base station only...
For the original query - you can change individual devices from the Asus app. Select the device you want to rename, then change it under System Settings -> Nickname.