Aternos does have a chestlock mod yes , but for 1.10.2 . I and my friends using aternos for 1.14.4 so i searched for a chestlock plugin which works in 1.14 and i have found that . I did not read the other mod suggestion threads so i hope you will add that mod or another chestlock mod works in 1.14 , thanks for making a perfect place for minecraft players and bye 
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Mod : https://www.spigotmc.org/resou…continuation-of-lwc.2162/