Urbackup change internet port

Hy Everyone,

I want to test urbackup 2.5. Here is my config: Server: Ubuntu 20.04LTS, urbackup-server ver. 2.5.18beta, no firewall, client: Windows 10Pro, urbackup-client 2.5.14beta.
I want to change the listening port. In normal mode (port 55415) internet client can comunicate with the server (file backup is ok).
When I want to change the port (ex: 5001), client says: Server unreachable, like in the picture.

Someone else with this problem?

put server URL : http://IP_ADRESS/5001 but not urbackup://

No luck
On the server only these values are acceptable:
urbackup://ip:5001 or urbackup://ip/5001
for other values the server says: "the internet server name should be a host name or IP "

You can change the server port in the advanced settings (to e.g. 5001). It can differ from the port the clients connect to.

In this case it’s working!!!
This means, that i must open 2 ports on the server: 5001 and 55415? Or i missed something.
Sorry for the stupid basic question.