Server Crashes when client connects in LAN mode

I'm trying to setup a dedicated server for LAN.
My first try was simply to start the "mncds - instance 0 - standard.bat" supplied by the dedicated server provided via hldsupdatetool. On the client PC I can't see the server on the LAN tab, but I can connect via console (open <ip>).
Thats why i decided to set the bIsLANMatch variable to true. The server starts fine, but still not visible in the LAN tab of the client PC. When I connect via console the server outputs "Client connection speed is 10000" and mncds.exe crashes after that.

While I can live with the first solution I would like a solution where the server shows up in the LAN page.

And yes I made sure the server browser shows empty servers, was set to the correct game type, and I disabled the software firewall (Windows Firewall) on the server.