Can you play with Ps4 on an Aternos Minecraft Bedrock server?
To the best of my knowledge, this is not currently possible. Not yet at the beginning of the year. But it may well be that it is now possible.
Just give it a try
With the Playstation version of Minecraft Bedrock Edition you can only play on official Microsoft / Mojang partner servers.
https://help.minecraft.net/hc/en-us/articles/360037725571-Minecraft-for-PlayStation-4-FAQ
U can play other custom servers on minecraft ps4 by an app called bedrocktogether on ios but still it doesn't work for aternos servers
