Aternos is a great minecraft hosting site, with the availbility to make a server to play with friends for free.
people can play it with just vanilla minecraft, or a modded one if bored
now here is my suggestions. Big mods such as RLcraft or Crazicraft takes up quite a lot of RAM. I know you're running this for free, and you won't be able to afford for more advancements, but if you can, i think you should differ the RAM that can be allocated to normal Vanilla server and a modded server.
i'm not trying to discriminate the player who play vanilla, but i personally think that it will be more efficient, as normal server doesn't require as much RAM as modded ones. Perhaps the normal Vanilla to 2.5GB and modded to 3GB? i would love if you could change it to 4GB, as if i constantly check on the RAM meter on my server site, it get close to limit.and we haven't even travelled to the nether and other dimension yet.
I would love new changes, or even good replies that would help us to play with less lag.Thank you in advance. 
EDIT: i've seen many people writing similar stuffs related to RAM problems, if you cannot change the ram size, i would love some tips in to reduce the lag for the server as i play RLcraft with 2 other friends and believe me, the lags hits me quite hard.
