Since upgrading to iPhone 17 pro my Apple Watch disconnects. Very difficult to get it to reconnect without resetting the watch : I’ve tried disconnecting Bluetooth on both devices - that only worked once, and several minutes later; switching the watch off and on.
iPhone 17 Pro
To rule out a software issue inside your backup data, erase the watch and pair it again, setting it up as a new device. You will only lose your created Watch faces and may have to activate the cards in your Wallet app again.
Unpair and erase your Apple Watch - Apple Support
In case it still does not work, let Apple Techs know by using the Feedback link:
Apple Watch disconnecting after iPhone 17 Pro upgrade
