There is a network profiler application included with the engine. It can show you a lot of information about how much bandwidth is being used, how many properties and actors are being replicated, and more. It is an advanced tool and we’d like to improve the interface in the future, but it should get you started.
It’s located at < your Unreal install directory >/< version >/Engine/Binaries/DotNET/NetworkProfiler.exe.
In order to view data in the application, you have to capture a profile while your game is running. To do this, enter the command ‘netprofile’ in the console to start recording and enter it again to stop recording. After recording stops, there should be an *.nprof file in your game’s Saved/Profiling directory. Open this file in the Network Profiler and you can see the statistics that were recorded.
Note that more information is recorded when profiling on the server, so you may find that more useful in debugging.