Hello,

I feel you.
I had already run several servers, mainly for groups of 3-7 players and often fought against exactly this problem.

The main problem is a peer-to-peer driven server model which is hardcoded.
This problem is not solvable unless the devs rewrite the code from scratch.

But you can take a look here:
https://jamesachambers.com/revisiting-fixing-valheim-lag-modifying-send-receive-limits/

- read everything on the site and all the comments below to fully understand the issue itself
- extract essential information for your needs
- follow these instructions
- thank me later

Best regards/