Your isSprinting bool ist Not replicated. What is Not working, Animation or Change of movementSpeed?
I have run into a multiplayer problem. Other clients and server can see my player sprinting but on the client, thats sprinting isn’t seeing himself sprint? here is my code
After putting IsSprinting on replicated, My movement speed is now working but the animation isn’t locally being played on client 1 but client 2 can see client 1 running and vice versa
So we fixed half of IT, thats good 
can you please Show your animBP animgraph and Bpgraph? You can also use blueprintue.com for this. Mostly the Part where you read or calculate the pawn movementSpeed or where you Access the isRunning bool
Ah, so you doing it good calculating the speed in the animBP! But as far as I see in:
https://github.com/EpicGames/UnrealEngine/blob/bf95c2cbc703123e08ab54e3ceccdd47e48d224a/Engine/Source/Runtime/Engine/Classes/GameFramework/CharacterMovementComponent.h#L253
The maxWalk speed you are changing is NOT a replicated Property. Sou you should change that in a Multicast which will change that value on server and clients, or use your Bool from the Pawn inside of you animBP Logic (sounds like multiplying the speed when bool is true - but doesn’t sound “clean” for me).
Here is a tested code - you could skip the SwitchHasAuthorit and call always the serverSet - it doesn’t make a difference - but I feel it is cleaner that way:
Thank you so much, This was a really easy fix.
I had a question if I want to run a branch to check some booleans before I sprint would I need to put the code in after the auth and the remote or just in the authority?
Hm, it depends on where you’re bools live or are Being Set. I would recommend, where possible, handle that stuff on the Server only, maybe you don’t need Them to replicate, If you send me more Details, I can have a Look.
problem solved? than please check the answer as correct