How to Host a Jaffa Factory 2 (Replica) Server

Start with 5 GB of RAM. That's the recommended floor for Jaffa Factory 2 (Replica) on Forge 1.20.1, and it's where most factory-automation modpacks with this mod count need to sit before you even think about adding players — going lower just invites garbage-collection stutter once machines start chugging.

Import the modpack directly instead of rebuilding it from a client export. Jaffa Factory 2 (Replica) exists specifically to match the exact mod list and configs from the Yogscast series, so a clean server-side import avoids the version drift and missing dependencies you'd get trying to reconstruct it by hand.

Watch the console through the first boot and don't touch anything until it says done. Factory modpacks generate a lot of config files and registry entries on first launch, and with this many mods loaded at once that process can take several minutes — a server that looks stalled is often still writing configs, not crashed.

Only invite players once that first boot finishes cleanly with no repeating errors in the log. Letting people connect mid-generation is the fastest way to get a world with half-initialized machine configs that cause desyncs later.

Take a backup before importing an existing world, updating Forge, or changing any mod configs. If you're trying to recreate progress from the Yogscast episodes or your own long factory chains, a bad config change without a backup can mean redoing hours of automation from scratch.