connection closed - mismatched mod channel list

So, me and my friends are trying to start a modded world. Me and 1 friend did a test run on the world yesterday, and it worked perfectly fine. However, on the next day I decided to create a new world, as we messed around on the test run ( spawning stuff etc ). We also decided to add JEI to our world, and we double checked to make sure we all had the same versions of every mod we put on aternos. However, when I tried to enter the server, it stated Connection closed - mismatched mod channel list. I got confused because we all sent screenshots and confirmed the right versions of all the mods, both on aternos and in forge. All my other friends also couldn't get in, they had the same issue. I deleted the world and made a new one, this time I ultra checked to make sure we had the same versions for every mod, as I sent the versions we will use in a discord server, which were also on aternos. But it still doesn't work, what do I do?

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