I have a ZMQ server listening on port 12345 TCP. When another server connects on that port locally or via VM it works fine, but if I try from a remote server that has to go through port forwarding on my Fios firewall it just bombs. The packets are showing up in Wireshark but ZMQ just ignores them. Is there anyway to get past this?
You shouldn't be able to bind more than once to the same port number, either from the same process or another.
ZMQ should give a failure when you issue bind with a port number already in use.  Are you checking return codes?
Incoming ZeroMQ traffic dropped by server due to NAT?