I have two AP6 where the one is with a LAN cable while the second works as mesh in another room.
I add two static IPs to both the APs
192.168.5.100 Master
192.168.5.101 Mesh
For some reason the second one doesn’t obey me at random times it decides to pick its own ip for example 192.168.5.123 (current one) despite the fact that i told it to use a static IP
The specific ip (192.168.5.101) is free and not occupied.
Do you have fallback upon failure switched on? I had an issue where one AP kept moving from 10.0. to 10.188 until i switched this off. It was most annoying as it looked like things were connected etc. but they weren’t reachable when needed as on a different subnet.