To join a private server on Roblox Xbox, start by using a second account on a different device. First, create a second Roblox account on either a mobile device or a PC. Next, add your Xbox account as a friend on this new second account.
Now, use the second account to join the private server. If you’re on mobile, tap the game, then tap the people icon with the play button. Create a private server and set it to “Friends Allowed.” On a PC, click on the game, then “Servers,” select “Private Server,” and set it to “Friends Allowed.”
Switch back to your Xbox account and navigate to your friends list. Find the second account in your friends list. Finally, join the session of the second account to enter the private server on your Xbox. This method ensures you can play on a private server using your Xbox.