Unable to get Cassandra in a Docker to talk to cluster
I think that the problem could be that you don't set the CASSANDRA_BROADCAST_ADDRESS parameter that is used by Cassandra when it talks with other nodes. By default it sets it to value of CASSANDRA_LISTEN_ADDRESS, but in  your case this address is address of Docker network, so other nodes won't able to reach your Docker instance.

You need to set CASSANDRA_BROADCAST_ADDRESS to IP address of your machine that hosts the Docker.