Just tried this. Backing up to a SNAP mounted USB disk, around 400GB of files.
UI keeps saying Disconnected from Backup Engine and the server end crashing and restarting. I checked the memory settings and they are defaulted to 128m and 1024m. I tried increasing but made no difference.
If I drop the backup set to around 200GB, 50k files, then it seems to work fine.
Which is the best log to look at?