Changing the server/bind-server does little as sometimes all of the servers throw same error. I face this problem when connecting ZNC to DALnet. Please fix this very annoying problem as it defeats the whole purpose of having/configuring ZNC if I can't stay connected.
I had posted about same problem a month ago.
The only way I could resolve the problem was when I wiped out my ZNC config & rebuilt another one and changed bindhost to 'C3' instead of 'C1'.
Looking back I think the problem was with the servers & how they handle SSL.
Edit - Forgot to add link to previous post - https://www.xshellz.com/community/general/48167/Can't-connect---SSL-error