Roon 2.0 - cannot import backup

Sorry, I tend to “jump”.

After getting stuck with the legacy version, I upgraded to 2.0 (which was now available).
The problem was the same, so I didn’t update the screenshots.

When I open the client I have to choose my Roon Core whichever is found.

The next window is the login screen. Here I can choose the option of backup.

After the update is complete, a reboot is required. Here comes (after resetting the NAS) the message that the client is waiting for the Roon Core.
Screenshot 2022-10-07 172258

Screenshot 2022-10-07 172102

After this restart, “Connection failed” appears

And I’m definitely in the right network with the right IP range.
When I reconnect, I’m back to square one with no backup in place.

After going wired, resetting the NAS, trying different routers, changing network cards…

The NAS works, I can see the traffic during the backup and also the network traffic. What I can’t verify is if the core actually has a connection the whole time.