For the first time in 3 years of owning my vehicle, auto-unlock didn’t operate as I approached my vehicle. Probably 5 or 6 attempts at getting the handles to extend failed as I approached the car, but the car unlocked and presented the handles immediately with two clicks of the fob. Of note, my car was parked in an underground garage with no internet access and the parking space was exceedingly tight. When I moved my car outside, the auto-unlock again worked perfectly, and it has continued to work since. I may have overlooked it in the manual, but what are the conditions for the auto-unlock to fail? Lack of connectivity? Tight spaces? Other?
Never had internet access be a problem for unlocking. But I have had interference be a problem — if there's a powerful radio or TV transmission tower nearby it can drown out the keyfob's passive signal. Or maybe after three years your keyfob battery is dying.
Having the fob in the same pocket/purse as a cell phone or other RF device. My gym keyfob will also do it, for example.
Proximity to another 'interfering' Bluetooth device in same pocket or fob battery might need replacing.