I also have this problem and from a reddit post:
https://www.reddit.com/r/unrealengin...m_medium=web2x
I can confirm that for my case it seems to simply be due to the fact that I have a VPN installed (PIA).
Unreal Engine only stutters when I am is NOT connected to the VPN.
So either connect to your VPN if you have one, or uncheck “Enable Transport” in UDP Messaging Project Settings in the meantime I suppose.