Unstable connection on Minecraft Bedrock during Local multiplayer

I got big issues playing Minecraft on local network with my friend because the game is heavily laggy.

Description :

- I am on windows 10, everything is up to date on my computer.

- My friend is on windows 11, and everything is also up to date on her computer.

- We both have a legal and up to date version of Minecraft.

- We connect on the same WiFi

- She launches a world on her PC, I join

- I also launch the task manager on my side to track the internet connection, and it highly fluctuates and reaches 0 every 5 to 10 seconds for about 2-5 seconds (the graph is like a sawtooth-shaped). And it's unplayable : my actions are not take into account and I have to do things twice every time I recover the full connection. When it remains at 0 for too long, I got kicked from the world.

I have Windows Defender and Windows Firewall, and she has McAffee. I don't know if it has something to do with our problem.

Any clue is welcomed !

Thanks!

:)