DIAGNOSIS The 2.4GHz Wi-Fi setup process is finicky. Most failures are due to phone settings or network conflicts.
FIX Turn off mobile data on your phone. Ensure your 2.4GHz Wi-Fi network is active (not 5GHz). During setup, when prompted, join the AC's temporary network (LG_AC_XXXX). Keep the phone close to the unit.
IF THAT DIDN'T WORK Reset the AC's Wi-Fi module. Hold the Wi-Fi button on the unit or remote for 5+ seconds until the Wi-Fi light blinks rapidly. Start the setup process over from scratch.
HEADS UP Some routers with band steering or mesh systems cause issues. A temporary guest network on 2.4GHz often works.