Connection to the mediation server bibi.hamachi.cc has been unexpectedly lost can be caused by the following.

• Peak hours when your ISP has a large amount of traffic and it is related to packet loss/latency. If the connection becomes too lossy to keep a stable connection with the server, it will drop the connection.
• Being behind a proxy/gateway that does not support persistent connections. This is less common, and if this were the case, you would have issues keeping peer to peer tunnels active.