Video call drops after 15 seconds if call from external

Hi folks,
I experience call drops after about 15 seconds if the calls initiated from external. It is working fine if the calls initiated internally.
I have got the ports enabled from my Firewall but still experienced call drop after few seconds as long as the call was initiated externally. Any clue and advices are appreciated. Attached are the var log:

jicofo.log.log (10.9 KB) jicofo.log.log (10.9 KB) jvb.log.log (25.3 KB) prosody.log.log (1.6 KB) prosody.err.txt (1.0 KB)