Cheats and commands work a bit different on a server than on the client.
While these have to be activated on a server, the server uses a operator system.
Grant a player operator rights
In order to grant a player operator rights you have to add them to the OP list. On Aternos you can easily do that on the players page:
- Navigate to Players -> OPs (https://aternos.org/players/ops)
- Enter your ingame name and press "Add"
That's it. You can now use cheat commands like /gamemode on your server.
Repeat this for every other player you also want to grant operator rights.
Grant a player operator rights (alternative way)
If the first method, for whatever reason, does not work for you you can try to op yourself using the console.
- Start your server as usual
- Navigate to the console page (https://aternos.org/console/)
- Enter op example (replace "example" with your actual ingame name)
Please note that if your server has cracked enabled this way might not work correctly. That's why it is recommended to OP players using the players page.
Additional step for Bedrock edition servers
For bedrock edition servers make sure to enable "Allow Cheats" on the options page.
If it's disabled you have to enable it and restart your server afterwards.