My phone uses VPN all the time, so many sites think I'm elsewhere. My watch tends to show the wrong temperature despite having the settings using the default phone GPS. If I set the location to a fixed location, it seems to show better temperature but still not what the official airport is.
What is even more frustrating is when recording the activity, my watch showed 104F which was rather accurate for that day, but the posted activity showed 88F! Not even close! I recorded a few other tests with various location settings; fixed and GPS located and no matter which for that hour time, they all came out with 88F. My girlfriend across town and with the same phone, using Vivoactive 4, got the same 88F.
The only thing I could figure is, the Garmin Connect may be sending the watch a list of temps based on a predicted schedule and updates every 20 minutes if near the phone. Changing source from VPN to non-VPN, fixed location/GPS, may not update the watch accordingly until some time later when it purges the schedule of temps.
Getting frustrating! Recorded a walk this morning and checked the temp on the watch recalling it was mid to upper 50'sF. The recorded temp shows 48F. That was using a fixed location I had set the night before.