Okay, the Port is not the problem.
The first line looks as if the target server reject the connection. Half a minute later no answer seems to pitch on the firewall.
FW Log:
Aug 17 09:31:09 10.25.15.22 framf02: NetScreen device_id=framf02 [Root]system-notification-00257(traffic): start_time="2015-08-17 09:31:05" duration=5 policy_id=1001 service=tcp/port:902 proto=6 src zone=bt-mgmt dst zone=bt-mgmt action=Permit sent=16576 rcvd=0 src=10.15.3.201 dst=10.15.5.219 src_port=50961 dst_port=902 session_id=171331 reason=Close - TCP RST
Aug 17 09:31:39 10.25.15.22 framf02: NetScreen device_id=framf02 [Root]system-notification-00257(traffic): start_time="2015-08-17 09:31:20" duration=19 policy_id=1001 service=tcp/port:902 proto=6 src zone=bt-mgmt dst zone=bt-mgmt action=Permit sent=279933 rcvd=0 src=10.15.3.201 dst=10.15.5.219 src_port=50980 dst_port=902 port=902 session_id=251722 reason=Close - AGE OUT
Any idea?`