Alright so I was gone from GMOD for a fairly long time, I stopped right before 13 came out. I had my own server but I had a very shitty host and I decided to run the server on a computer made solely for hosting different game servers.
So I followed this tutorial:
And I did everything it said and made a shortcut to start the server. When I start it up I get this:
Console initialized. ConVarRef mat_dxlevel doesn't point to an existing ConVar Game.dll loaded for "Garry's Mod" Initializing Steam libraries for secure Internet server osversion.cpp <186> : Assertion Failed: Unknown osvi.dwMinorVersion, assuming Windows2k8r2: 2 Assert( Assertion Failed: Unknown osvi.dwMinorVersion, assuming Windown2k8r2: 2 >:osversion.cpp:186