At one point MTU was raised to 1024 (mentioned in 4.9 release notes: Unreal Engine 4.9 Released! - Announcements and Releases - Unreal Engine Forums )
But then it was lowered again to 512:
Engine/Source/Runtime/CoreUObject/Public/UObject/CoreNet.h
Here is the git commit where it happened:
https://github.com/EpicGames/UnrealEngine/commit/6ab7fcd2462da40fb63e4454788013741526affa
It says:
“Added comment to enums in CoreNet, changed MTU back to 512 until discussion on this topic has finished”
What were the downsides? Any further conclusions on this? I’m sending some small unreliable video data and benefit from a bigger MTU. I’ve set it to 1024 for now, but what are the ways that this could bite me?