Diablo II: Resurrected (D2R) , the "LFS Mod Offline Fix" typically refers to community-developed patches or configuration changes designed to bypass the game's requirement to connect to Battle.net every 30 days for authentication. Key Methods for Offline Play & Fixes JSON Settings Modification (Console/Switch)
Even with the fix, you may encounter issues. Here is the symptom-to-solution map. diablo 2 resurrected lfs mod offline fix for v verified