@Vanguard-01 I had all these error messages, and this is how I fixed them. *Note* I do not know if these are the only issues that cause these error messages. Handshake Error = not using same versions Your server, and your friends client, are two different versions. The versions must match for them to "Handshake". In your server folder you will find a file called git-version.txt. In your friends KSP directory, in the GameData folder, he will also find a get-version.txt. Both your git-version.txt and his get-version.txt files must match. You both must have the most recent development build to play on the most recent KSP update. Unhandled Exception = firewall/antivirus not allowing the server (this also applies to the client if KSP.exe is not allowed through the firewall) Programs sometimes need exceptions to do what you want them to do when dealing with the internet. In the case of the server, DMPserver.exe needs an exception. In the case of the client, KSP.exe needs an exception. Failed To Connect = Port is not open To open ports you must forward them. On the bottom or the side of your router you will find the make and model. Then google "Router Make and Model Port Forwarding" for a guide. *Note* Again I say I do not know if these are the only issues that cause these errors. This is just how I solved them.