Quick Answer
A quick troubleshooting guide for China connectivity: the most common setup failures for SIM/eSIM, what to check first, and how to get back online without burning an hour.
Why it matters
Often it’s a mix of weak signal + app session issues. Reopen the app, switch networks if possible, and avoid basements or crowded station corners when paying.
TL;DR (Copy‑Paste Summary)
- First check: data roaming setting (yes, even for some eSIMs).
- Second check: APN is correct and selected.
- Fast reset: toggle airplane mode + restart + reselect the data line.
The 60-Second Fix Order
- toggle airplane mode
- confirm the correct line is used for cellular data
- enable data roaming if your plan requires it
- check APN
- restart phone
FAQ
Why do my payment QR codes fail when my data seems fine?
Often it’s a mix of weak signal + app session issues. Reopen the app, switch networks if possible, and avoid basements or crowded station corners when paying.
