"not ready" for self hosted RustDesk - OSS needs port 21114 open?

[AntonTrapp]

I installed the latest docker image and had massive connection issues - only about 1 out of 20 times my clients have been able to connect. The rest the server never was "ready".

After opening port 21114 on the server (### OSS version - "TCP): used for web console, only available in Pro version.") every client can connect all the time immediately.

So I guess that there is an invalid request from the client (1.3.7 and nightly 1.3.8 from today) to that port or the documentation should mention that this port should always be open.

PS: Apart from that: this thing is incredible easy to install and lightning fast. Impressive work!