Some players may encounter a “Connection Lost - Network Protocol Error” when trying to join the server. This issue is typically caused by an outdated or corrupted client installation of the modpack.
This error usually happens when:
Your local modpack files are not properly installed
Some mods are missing or mismatched
The pack version does not match the server
Solution: reinstall the modpack installation
Option 1: Modrinth (Recommended)
Delete your current installation of the modpack, you may want to save your map files.