At this stage I think Time Machine is barely fit for purpose for backing up over the network. I've lost days on this issue over the years too.
I have always been totally confused as to whether I should be using AFP or SMB (tried both). As others have said, SMB often seems very unreliable, and AFP is supposedly being deprecated...
Mounting network shares from my Synology to Mac(s) is never flawless either. As other comments have noted, this experience is very much worse than what it used to be like in Windows (not that I've mounted network shares in Windows for a while).