Port, connection refused

[Cliff-R-K]

I tried following the guide for setting up the passthroughvpn. I am trying to get a mysterium node docker up which uses webui-port 4449.
I have added --net=container:passthroughvpn to the extra options in the mysterium container. But if I also change the network to None it will not start.
I also created the port 4449:4449 and added 4449 to the additional port settings in passthrougvpn.
But I cant reach the webui of the mysterium container. Have I missed something ?