If you don't want to play ARK Survival Evolved on the latest public version and would rather play a different beta branch to play older versions such as pre aquatica, here's how to change the version of your ARK Survival Evolved server.

When changing server versions, you must also change your ARK SE game version to match the version of your server. The process for downgrading your game version can be found here.

Danger

Changing your ARK SE server version risks corrupting saves and breaking mods. As this deletes everything, download a backup to your PC first if you want to keep your save.

Changing Steam Beta Version

1
Log in to Bropanel and Stop your server.
2
In the sidebar, go to Settings.
3
Edit Steam Beta Branch with the version you want to use (A list of versions is below).
4
Click Reinstall in the top-right.
5
Select Format (keep settings), then confirm and wait for the install to finish.

Here are the currently available beta branches to choose from. They can be found here:

ARK Survival Evolved Beta Branches.

The latest version is public, preaquatica is used to downgrade to the latest version before the Aquatica update.