Before I go out and split firewood to vent my frustrations, I'm going to post about this issue in case either 1) the act of doing so gives me insight or 2) someone out there has any ideas.
I have two computers here. Let's call them Workstation and Server. I also have two NAS, let's call them Asustor and Synology. Last week, Workstation was running Linux Mint 21 and Server was running LM20. Both could connect to both NAS and transfer files at expected speeds. In particular, they each back up to Synology every night.
Yesterday, I upgraded Server to LM21. Today, its transfer speed to Synology is AWFUL. To put it in perspective, a backup that normally takes 30 minutes was 2% complete when I stopped it at 7 hours.
Now both Workstation and Server are running LM21, both are using kernel 5.15.0-52, and both have the exact same line in fstab to mount the SMB share. One works fine and one sucks mightily. Server can still copy files to Asustor just fine. Only Synology is an issue. If I browse the network and mount the Synology share that way, things copy fine. It is only when it mounts via fstab.
This is the censored line I am using in fstab (the line for Asustor uses the same options).
//***/idrive /mnt/idrive cifs noauto,x-systemd.automount,username=***,password=***,file_mode=0777,dir_mode=0777 0 0
I have also tried this simpler version with the same result:
//***/idrive /mnt/idrive cifs username=***,password=***,file_mode=0777,dir_mode=0777 0 0
Oh well, writing all this down didn't give me any new insights...
