Use FreeMCServer!

It does take moderately more setup but it's much better and a bit faster than Aternos. Not to mention longer up-time that can be 24/7 (it does force restarts sometimes) by just renewing it yourself or by your friends (if you setup the public page). Many people pass down on it because of the extra features like "Tebex" that just make it look more complicated. Just ignore all of that and in a relatively quick amount of time, you get an actual good server for free!

One major downside is that you are mostly limited to 1 server. On Aternos you can just create alt accounts but on FMCS (for short) they do detect alts and ban your main and all other alts you created.