In some scenarios a Tunnel client server's hub.log may display communication errors with other Tunnel client server via port 48002 even though Tunneling is properly set and is successfully communicating with it's Tunnel server.
Example of error seeing in hub.log with loglevel 3.
sockConnect - connect to 188.8.131.52 48002 failed 10060
ihubrequest: SessionConnect failed: 184.108.40.206/48002
hub: hubup - send failed for /UIMDomain/OtherTunnelClientHubName (220.127.116.11:48002 communication error)