How do I switch my game properties to the be able to play on the Dev servers?

[Elety]

I can't join any of the dev servers :(

[Maverickroll]

Are you asking how to get the dev branch on Steam, or how to join a server?

To get the dev branch, right click the Rust icon in steam and go to Properties, click the Betas tab, and in the drop down menu select Dev - Live Developer Branch. Steam will then patch you to the latest dev patch.

If you're asking how to join a server, in the past as far as I've seen you haven't needed a compatible server for the game with the latest dev patch. But since this dev patch added a lot of new buildings and crafting recipes, servers need to update individually. You need to find a server running the current dev branch patch. There are a couple so far.