Had this issue in multiplayer as well. I run the dedicated server on my PC that I'm playing on and others connect to it. My wife and I would play and if we both were in our main base opening chests, doors, etc. just didn't work.

There is a bit of a hack work around that people have come up with.

TL;DR:

It involves modifying the server and game .dll files to increase the data transfer limit between client and server. Currently it is capped a specific number which is too small to cope.

I modified the files for the server and clinet on my pc as well as the client on hers and now we can play without issue. Took about 15m to read how to do it, get the software for editing and modify the files.

Obviously you do this at your own risk, so back up your save data.

https://jamesachambers.com/revisiting-fixing-valheim-lag-modifying-send-receive-limits/

Edit: Oh, not sure if this makes a difference or not, but I also change the priority for the server run at "above normal" (set in Windows Task Manager)