Ok referring to connections.
It's the default values: 2 retries and 5 secs delay.
But i think it's what TCD says. If Filezilla doesn't break upload connection with server, all is well. If breaks, then the bug!
Let's see if all goes well with Speedball2, if not. Reverting to 3.0 or 2.2 I'm afraid!
I'll analyze your link. And see if it's referred.