RPC: improve error message on connection failure
RPC: improve error message on connection failure
before:
Initialization of fx42 FAILED
[0] gaierror: [Errno -2] Name or service not known
after:
Initialization of fx42 FAILED
[0] CommunicationError: socket.gaierror connecting to wid421:8000 - ERR no -2 : Name or service not known