I have a watchOS app on a cellular Apple Watch (Series 11, watchOS 26.6) that periodically uploads small HTTPS payloads to a backend. It needs to keep working when the paired iPhone is absent and the watch is on its own cellular connection.
What I observe:
- Foreground, no phone, cellular: uploads work.
- Background, no phone, cellular-only (no Wi‑Fi): nothing uploads for hours.
- The instant the watch joins Wi‑Fi (app still in background): the whole backlog flushes at once via my background URLSession.
My questions:
- Is a background URLSession transfer over cellular ever expected to run without Wi‑Fi (e.g. while charging), or is Wi‑Fi effectively required in
practice? Any configuration that improves the odds? 2. During an active HKWorkoutSession (which keeps the app executing), will a high-level URLSession data task reliably complete over cellular with the phone absent? And is using a workout session to keep a non-fitness background uploader alive acceptable, or is there a sanctioned alternative? 3. Is there any other supported mechanism for periodic background cellular upload from a phoneless watch that I'm missing?
Any help would be greatly appreciated. Thank you!
