Valheim now supports crossplay between players who purchased the game via Steam and those who purchased it on the Microsoft Store.

In the recent update (Patch 0.211.7) for Valheim's server, a new command line parameter was added to enable crossplay. It is not enabled by default.

Please ensure your server is running on the latest available build of the Valheim server software before enabling crossplay.

Enabling for a ServerFlex Valheim Server