I have a Garmin Edge 1030 Plus which syncs perfectly with Strava but only if I'm at home (i.e. when both my iPhone X and Garmin device are on the same WiFi network). However, I've seen other Garmin Edge 1030 Plus devices that will sync to Strava even if not near a WiFi network (by just using Bluetooth); in fact their Garmin devices will sync to Strava as soon as the ride ends. I cannot seem to find that setting anywhere on my Garmin device or Garmin Connect. Does anyone know?
Please note that my Garmin device is synced to my iPhone; when I get a notification on my iPhone, it shows up on my Garmin device. It just will not upload the routes to Strava (unless they are both on the same WiFi network).