Handsel

I have been looking around for about an hour, and I cannot find anything on my issue, but just lightly touched on. I have a "handshake failure: Incompatible HANDSHAKE_REPLY message" Other people can connect to the server (Using port 6702), but I cannot connect to any servers using this port, or any servers at all. Same message for all servers. I would really enjoy an answer or direction to an answer. I appreciate it in advance.