Hi, osx user here.
I have installed a simple Cassandra db on my laptop and I would like to query it outside the Lan.
So I set port forwarding and port triggering on my router (vodafone station) to link external 9042 to internal 9042.

Moreover I set on cassandra.yaml the broadcast_rpc_address to my router ip.

Unfortunately, when I try to connect using java api I obtain:

Exception in thread "main" com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /HERE_THERE_IS_ROUTER_IP:9042 (com.datastax.driver.core.exceptions.TransportException: [/HERE_THERE_IS_ROUTER_IP:9042] Cannot connect))

I noted that without setting broadcast_rpc_address I can reach Cassandra trough so the database is active and running.

I’ve also tried  

lsof -n -i4TCP:9042 | grep LISTEN

and I obtain 

java    7555 giordano  184u  IPv4 0x513195612572e265      0t0  TCP (LISTEN)

when I unset broadcast_rpc_address
and no output when I set broadcast_rpc_address.
Is the problem in the yaml settings on in the router settings?

P.S.: I have also modifying listen_address in the same way, without good news.
P.P.S: clearly each time I edited the yaml file I restarted cassandra