Connection Error message after upgrading to OS5

After Upgrading to OS5 I constantly get this error message on my screen:
There was a problem connecting to the server “MyCloudEX2Ultra”.
The server may not exist or it is unavailable at this time. Check the server name or IP address, check your network connection, and then try again.

I can connect to the drive via the finder, I just can’t stop the constant error messages from popping up.

And my time machine does not work anymore