Here is a breakdown of why this happens and how you can get past it. Why does LGUP say "Model Unknown"? LGUP is a sensitive tool. It relies on a specific DLL (Dynamic Link Library)
Starting with Android 8.0 (Oreo), LG introduced Anti-Rollback (ARB). The phone’s bootloader reports a rollback index. If LGUP detects an ARB mismatch because you previously flashed a different firmware, it may refuse to identify the phone. lgup model unknown
If the COM port number is very high (e.g., COM40), right-click it, go to Properties > Port Settings > Advanced, and change it to a lower number like COM10. UpperCut: The Alternative Solution Here is a breakdown of why this happens