Add custom connect failed error message?

If the client tries to connect to a server, which is not running, a gRPC error message will be returned.

Maybe it is more user friendly to add a custom error message for this exception?

command:
client -l -s="localhost:1234"

output:
dhbw-blackboard-client: Oops, there was a RPC Problem: Unavailable (Connect Failed)
Try `dhbw-blackboard-client --help' for more information.

desirable output:
dhbw-blackboard-client: No connection to the host.
Make sure you enter the correct host address and port and check if the host is running.