A super simple and light weight C# HTTP Server (using .Net Framework 4.6 class library) that serves a single webpage in local area network.
Once in a while when I try to play Unreal Tournament or ICT Zombies with my roommate it turns out we cannot find each other even though we are under the same network (Bell home internet). After some trouble it becomes evident changing a router (e.g. using a customly purchased TPLink Archer instead of provided Bell HomeHub 300) can solve the problem. In such circumstances it's necessary to have some utility tool that is known to be simple enough to work in LAN environment thus we can quickly rule out the possibility that it's the program itself (e.g. Unreal Tournament is no longer maintained so we might expect it to just "no longer function in LAN") that's not working - but rather turn our attention to the network itself.