This little injectable DLL should fix the network bandwidth issue in valheim. It's based on this dnSpy patch method. The server also needs to get this DLL injected or patched by the dnSpy approach.
I'm currenty unable to build it using the correct mono runtime.
It uses reflection to find the loaded assembly_valheim in the current AppDomain and tries to set the private field m_dataPerSec in the singleton TDOMan.instance.
The program gets the current value and multiplies it by the factor 10 as suggested by the referenced article above.
I added a simple Injector Program using the Reloaded.Injector Library.
After Injection the Initialize-Method will be called by the injector.
Just clone this repo and open the solution in visual studio. It's current target .NET Framework is 4.5 but you could change that to whatever framework you have installed. The referenced helper NuGet package DllExport may prompt you to apply some patches to the project file. Select the only project file in the solution and press apply.
I am not aware of any kind of anti cheat in this game. But if the developer decides to add one, you'll get a ban when using this.