RTMP server - can't connect from third party apps

I’m trying to connect to the Manycam rtmp server from various apps, but I’m unable to. It works perfectly from the Manycam mobile app, but not from Larix or DJI Go.

I’ve tried the following format without success:
rtmp://ip-address:port/stream-key

The apps I mentioned don’t have a separate field for the stream key like the Manycam mobile app, but it should be fine to include it in the URL?

What is the correct URL format or is there something else I need to do?