Followings

It's not. Can you please open a case with tech support and send logs from the computer?

It is failing during your maintenance windows. Not all but a good deal will. I can bet you during your "Maintenance" tonight I will have a good deal of failures.

I will get the message

An error occurred (code: 1003)
The remote server returned an error: (503) Server Unavailable.

I just checked. It happened on the 13th. Not every workstation. This also happened on local backups.

So are we supposed to not run backups during this window? I had 27 backup failures last night. That's not a normal.