Unable to add Matter device

Hi,
im unable to add an aqara smartlock 200u to my existing matter network.

i have a homeassistant yellow poe on my unifi dreambox se in the basement. the signal from the HA yellow cant reach ground level. my wifi access point (2.4Ghz / 5Ghz / 6Ghz) is on ground level. i have an aqara Hub m3 matter enabled hub connected via wifi.

i can connect it to aqara app, to apple homekit (via iphone, i dont have an home pod)

once i connect homekit to HA it shows everything thats been setup within homekit except the lock… adding the lock via HA Companion App as a matter device wont work either.

i had it working a few days ago (dunno how i managed it though, was lucky i guess…) but now an update messed it up again.

Is there a way to start completely from new, as there was never a matter/thread network in my home?

i tried to delete everything matter related from my iphone, deletet the homekit homes and devices and deletet everything in settings-general-matter devices.

deletet every node from HA too, but once i try to setup everything again it shows up under a matter device/network im not using anymore for a few months now… im absolutely lost. can someone help me out here?