This hsould help you determine on which port(s) connections were coming through from the client to the database server:
SELECT c.session_id, c.local_tcp_port, s.login_name, s.host_name, s.program_name

FROM sys.dm_exec_connections AS c INNER JOIN

            sys.dm_exec_sessions AS s on c.session_id = s.session_id

WHERE c.local_tcp_port <> 1433