By default, GoCoder would be using 1935 port to push the stream to Wowza Streaming Engine.
The issue could also be related to the bitrate at which the video and audio are being encoded. Try lowering the bitrate for video and then see if the same issues happen again.
I was facing the same issue and I tried the host address: origin.cdn.wowza.com for broadcasting and edge.cnd.wowza.com for playback and now it works on 4G as well.
That is the correct way to stream ULL streams. Broadcast should always be going to the origin.cdn.wowza.com endpoint and playback from the edge.cdn.wowza.com endpoint.
This will ensure that the played back stream is pulling from and edge location closest to the end-user.