Duckwhale

The packet the server sent in response (to the client) is not known, and thus you can't connect. At least that's what I'm reading from the log. If so, you'd have to configure the client to understand the packets that the server uses, or configure the server to use an older packet version (that the client can understand). Either way, communication won't work unless both are speaking the same language. Evidently, they're currently unable to understand each other. Since ROB is quite old, I'd expect it to use older versions, so downgrading the server's packet version would be easiest.