So I spent three entire days straight making an Attack of the B-team styled "modpack" (really just putting mods on a server), which included getting all the right mods in the right versions, tweaking ore generation, and looking for a perfect seed. Working fine in singleplayer, i load up the server only to constantly be rubberbanding to the point of insanity (and being basically unable to fight mobs as they'd be standing still one moment, then jumping all over me the next with half my health having suddenly disappeared). I never got more than 3 connection bars, my friend (after what felt like 10 mins of loading in) couldn't get more than 1 and said it was 'literally unplayable' while my girlfriend couldn't join at all and was infinitely stuck on the 'logging in' screen.
I'm at my wits end right now. I've lowered the server view distance and done everything i can to reduce the load (including allocating EIGHT GIGS of ram to the modpack on my computer and removing six large mods from the pack) and I don't know what to do.
I've hosted servers/been on hosted servers before and never had any of these issues at all (and i've got good wifi too).
Any advice would be great. I can post the log/modlist if needed.
Playing on forge 1.12.2