ORA-28547 on database startup (Windows)

I had a couple of databases on Windows (10), which I basically left untouched except for the data files. After a clean shutdown, I backed up these files (including controlfiles). Nothing really happened since then, apart from an upgrade of Windows (10 → 11)

I mainly and only used the database for connection as SYSDBA, some of the databases have an additional user setup but I didn't setup a listener, never connected otherwise than local. That now must remain the same … but, after restoring file, I get the below error. There's no alert.log change.

The error points to network related setup, but since I basically have nothing setup specifically, the issue could be anywhere (in the network). Given the WIndows upgrade, there may also be a change in the OS account, and that's a rabbit hole I'm not going to explore but it may be where things are actually changed. It shouldn't be that hard to get it fixed, but note that I have no control whatsoever over the network, and also no control over network settings on the machine itself. That's the reason why no listener was setup. Obviously, the installer did install