I think you should check again your firewall settings. The log contains consistently the same error connecting to host 10.2.5.100 at port 902 for several conversion attempts:
2013-12-23T17:54:12.772+08:00 [01212 warning 'Default'] [,0] [NFC ERROR] NfcNewAuthdConnectionEx: Failed to connect to peer. Error: Failed to connect to server 10.2.5.100:902
As Rosen wrote, Converter server machine need to access the ESX host at port 902 for the conversions to succeed.
HTH
Plamen