I'm trying to run 2 modpacks called Slightly Vanilla Flavored and Better Minecraft Modpack, both forge from Overworlf Curseforge. I was at my friend's house with my laptop (all computers involved are more than capable). At his place in the past, we were able to play Slightly Vanilla Flavored with no issues. We would just hit the Open to Lan button and the other would jump in that way. That's how we always do it. Last night, we tried to do this exact thing again only this time, we had an issue. The joining party would join for a slip second and then leave the game only to get the error: an existing connection was closed by the remote host. If we switched places, internal server error. We both disabled the firewalls completely, disabled the antiviruses, and reinstalled everything except for our main vanilla Minecraft clients which we knew wouldn't get us anywhere. At the end of the night, we were able to just play straight vanilla with no issues with Lan multiplayer. I went home and found out I can use Lan with my brother's account with my laptop and desktop in vanilla, Optifine, and Forge installation inside vanilla client. So with that out of the way, Slightly Vanilla Flavored and Better Minecraft Modpack still didn't allow me to connect with the exact same issue. I'm also able to connect to a friend's server and Lan world Pokehaan Craft, Farming Valley, and a few other random packs that I just decided to mass download. New Beginnings was the only one I downloaded that allowed a connection with Lan, but I'm guessing it's such a resource hog that it kicked my laptop off in the same fashion but only after about 3 minutes. Does anyone have any answers as to why we can't Lan connect the two modpacks we desperately want to play? One other piece of information. With the correct Forge vanilla installation setup and slinging all the mods from the 2 packs in the mod folder. it would cause even the vanilla forge client to do the same to us. Any solutions to this would be appreciated. Reddit completely ignored me and I've been searching solutions and trying them out for around 12 hours now non stop.