Failure to respond is often a transient thing. If a host doesn't respond the first time you request a download, that doesn't mean it isn't live and won't answer later. But Gnucleus will now give up on it. Also, I've seen some clients fail to send a complete HTTP response if they are busy, and Gnucleus appears to consider this to be a connection failure. It isn't, since the host is live, and Gnucleus shouldn't give up on that host.

Gnucleus used to have the best download retry algorithm around. Not anymore.