If you are flying from Singapore to Shanghai for a short trip, the connectivity decision is usually more important than people think. Shanghai is easy to move around once you land, but getting reliable data, map access, and payment access sorted early can save you from wasting your first evening on airport counters or hotel Wi-Fi troubleshooting.
For most Singapore travelers, the practical choice is simple: use an international eSIM if your phone supports it, or rent a pocket Wi-Fi if you are traveling as a pair or a small group and want to share one connection. A Singapore roaming plan can also work, but it is usually the most expensive option unless your plan already includes generous mainland China data. The real tradeoff is not just speed. It is whether your setup can keep working after arrival, whether it needs physical pickup, and whether it gives you enough freedom to use maps, ride-hailing, messaging, and work apps without stress.