Re-pair Apple Watch without resetting
I have an Apple Watch 3 (model A1859 ) and iPhone 6 all with latest software. After about 3 months working fine the two lost contact a few days ago and activity is not updated on the phone anymore. After restarting both devices a few times I found instructions on the internet to unpair the phone and watch, which I did. As a result the phone and watch do not see each other anymore, although the watch happily talks to my MB pro to unlock it.
I would like to re-pair the phone and the watch *without* resetting the watch to factory state since it has data saved for a couple of days that is not on the phone. However, when I try to manually pair the two, the watch does not show up in the list on the phone.
How can I force the watch to go into pairing mode without resetting it?
Other solutions?