I connect a xiaomi repeater to my Asus rt-ax92u but i have a big problem with many disconnections of the clients that is connected to repeater and with messages with duplicates IP. My Asus router put the clients of xiaomi repeater to wired clients. Any idea?
If common fixes don't give results (and nobody has any further input here for you), I would be doing a full reset at this point. The network/routers are obviously not in a good/known state.
While it isn't guaranteed to solve anything, it will at least give you a clean/fresh state to begin actual troubleshooting. And not just chasing gremlins from a series of 'dirty' upgrades.
Replace the repeater with another AX92u. You can then connect them together in AiMesh mode.
I was in a similar position when I used Wireless repeaters. I was never able to get a stable network. I don't beleive Asus is the problem here as every other consumer network I've seen with repeaters suffers from the same issues.
My AX92u mesh solved all these problems.
One thing you should definitely try first it to update the firmware on your AX92u. There was connectivity issues with the early firmware.