Had the same problem after buying my Polar (and setting everything up). Wifi was working for the first time. Second morning, after return from run, auto upload did not work and had to sync manually through BT. Then I deleted my wifi settings, restarted watch and added wifi again. After sync with Garmin Express since that time all is working flowlessly. If this won´t help, please refer to topic here on forum, where similar problems related to hidden/ safe wifi router occured.
