Only one video window enable

Dear jitsis,

after some time of playing around with self hosted jitsi and set some meetings with parents and childrens successfull i see in some cases that only one of two windows.

If i set the browser debug tools to enable, this message appears often

2020-04-17T14:53:38.240Z [modules/RTC/BridgeChannel.js] <e.value>: Bridge Channel send: no opened channel.

If i use the same config on meet.jit.si everything works. IMHO should be a little bit adjusted somr things at my jitsi server. Can anyone help me?

I am using docker-jitsi-meet in my config.

Thanks in advance!