I am experiencing similar struggles with my BPIR4 that I upgraded (using OWUT) from 24.10.5.
The unit often becomes unreachable at all via ethernet (gui or cli) and I have to resort to the serial console to reset it using firstboot && reboot.
The behaviour of LuCi has changed recently in that when I attempt to change the lan IPv4 address, it does the 90second countdown, waits ~5second, only then does it give the option to make the change without verification and does another 90s countdown -- and mostly fails.
I had been lucky enough to get it to change once, and I made a backup of that configuration, which will load and work after a reset.