'a fatal error has occurred, connection has been terminated' help

I see that the problem regarding this message popping up is always different so I've resorted to asking for help here. I cannot seem to access the server while my freind can, I've tried redownloading my mods and Minecraft too. could this be an issue with aternos itself? if its any help were playing on 1.12.2. ive also provided a screenshot of the list of mods.