
Apple Watch depends on the iPhone for almost all of its functionality, connecting to and communicating with the iPhone using two methods: Bluetooth and Wi-Fi. If your iPhone and Apple Watch are connected to the same Wi-Fi network (an Apple Watch connection to a known Wi-Fi network is established through the iPhone), they can be as far apart from each other as the Wi-Fi signal will allow.
The two devices are also connected to each other through Bluetooth. Bluetooth requires both devices to be within 30 feet of each other or they will disconnect.

A few days ago, I experienced an issue that showed my iPhone and Apple Watch disconnected, even though they were on the same Wi-Fi network and only about two feet from each other.
While I don't know why it happened, I do know how to fix it. If you run into the same connection problems, give these quick fixes a try.
Airplane Mode
If you see the disconnect icon the first thing you should try is Airplane mode on Apple Watch to end and re-establish a connection.

- From the watch face on Apple Watch, swipe up from the bottom of the screen.
- Swipe to the right until you see the Control Center.
- Tap the airplane icon to turn Airplane mode on.
- Tap it again to turn it off.
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Article Link: What to Do if Your Apple Watch Disconnects From Your iPhone