This is mean that your external address and port is not available for the satellite.
Here you need either forward 28968 to 28968 for the second node or update your docker run command to use 28967 for listening and 28968 for the contact address, i.e.
-p 28967:28967/tcp -p 28967:28967/udp -e ADDRESS=xx.xxx.xx.x:28968
You have this choice because the second node on a different PC, if it would be on the same PC as a first one, then you should use a different external port everywhere, i.e. forward TCP+UDP 28968 to 28968 and have port mapping -p 28968:28967/tcp -p 28968:28967/udp -e ADDRESS=xx.xxx.xx.x:28968 in your docker run command.