I ran the server today to fetch example logs but the issue appears to have been resolved. Might've been a stroke of luck or an edit by you guys, but thank you for the help!
Posts by mustardpudding
After a recent update to the Create Live 2 modpack (both to its provided server files and client), we are unable to connect to the server due to a "mismatched mod list" even after updating our client locally and reinstalling the server software (switching to random version of Minecraft, then switching back to the modpack).
Self-hosting Create Live 2's provided server software works flawlessly, so the modpack update did not appear to break anything.
Observing server logs, not all advancements appear to be registered (only ~900 instead of the usual ~1700) and structures from Quark are not recognized when the world is deserialized.
This seems to be an issue leaning toward Aternos's end but I could be wrong; any ideas?