Hi, I have the same problem with connecting the gazebo by the Android qgoundcontrol.
IP of the Ubuntu running gazebo is 192.168.1.104, and IP of the phone running Android qgroundcontrol is 192.168.1.103. They can ping to each other.
In qgroundcontrol, I add the TCP link of '192.168.1.104:5760', then connect, but it fails and warns 'Error on socket:Connection refused.'
if anyone has the same problem?