Windows 10 Home.
Backup server isn't currently working for me.
If a file fails downloading, I disable my primary (astraweb, maxage 0) and backup (tweaknews, maxage 0), and enable another primary (tweaknews, maxage 0). Then the file downloads completely and successfully. I've set the primary tweaknews connection to connect while idle, and it connects and authenticates.
I've seen it work in the past with the new system of concurrently connected primary and backup threads, it just doesn't seem to be doing it's job in the recent past. I've just been manually downloading corrupt astraweb files from the backup server for the past month or so.
When it happens again, I'll add logs.