you know how much pain I had because of this not working !?
I tried this a year ago and gave up...
Now I connected the OMV PC via LAN to the router and everything just works. Why?
Why doesn´t it work through Wifi?
Now even the router shows the connection to homeassistant.
Well then the OMV PC has to be in the main room, where the router is ... I wanted it to be in the hallway.
At least and at last it now works. Jesus!