Minecraft server AFK?

How can you stay on a server indefinitely while being AFK? It doesn't work with an AFK fountain.

Do you have access to server.properties?

Anti-AFK hack
Script that presses W and S again and again
Put something on the W key so that you run continuously and always use pistons or water to get you back to the starting point.

Yes, but I don't want to extend the idletimeout, I want to remove it completely

Then turn it off:

player-idle-timeout = 0

Oh lol I didn't know xD

Player-idle-timeout = 0
or
player-idle-timeout = -1

Is that also possible with Aternos?

If you have access to the server.properties yes. Should go with any provider, including Aternos.

OK thanks