Modded Minecraft Servers for 1.17

You need the same pack the server runs

A modded server runs a mod loader — Forge, NeoForge or Fabric — and you cannot join it with a plain client. You install the same pack the server runs, usually through CurseForge, Modrinth, Prism or the ATLauncher, and the version has to match exactly, down to the pack build number. Servers that publish a pack code in their listing save you an hour of guessing.

Packs come in flavours. Kitchen-sink packs like All the Mods throw everything in at once; expert packs gate progression behind a recipe chain that takes months; magic, adventure and modded skyblock packs are different games again. The pack decides what the server is far more than the server rules do.

Because mods are heavy, ask about memory and chunk loading before you commit. A 300-mod pack wants six gigabytes allocated on the client, and a server that bans chunk loaders makes most automation pointless. A modlist you can read before joining is a good sign; a refusal to share one is not.

1.17 is deliberately half an update

Caves & Cliffs Part I shipped in June 2021 with the blocks but not the terrain. Copper, amethyst geodes, deepslate, candles, the spyglass, the lightning rod, powder snow, axolotls, goats and glow squid all arrived. The new cave and mountain generation was held back to 1.18, six months later.

That split is worth knowing before you join. You can mine copper and amethyst, but the world still generates the old way, with a floor at Y=0 and the narrow cave systems of earlier versions. Ore distribution follows the old curve too, so diamonds sit at the depths people learned in 1.16 rather than down near the new bedrock.

Very few servers stay here by choice now. The ones that do are normally running a modpack or a plugin that never got updated, or they are an established world that did not want a visible 1.18 terrain seam through the middle of it. It plays fine — it is just an unusual place to start.