Cannot connect Edge 840 to iPhone

Cannot connect Edge 840 to iPhone. I have tried so many options as recommended but they simply will not pair.

Edge 840 all reset.

 iPhone 12 with iOS 17.7

Used scan option with camera.

Used Connect App.

The Garmin will also not connect via USB to my Mac (OS 26 Tahoe) so Express app not much help. 

All good last week but suddenly disconnected. 

ChatGPT was pretty useless too, constantly giving me incorrect guidance. 

Can you advise please?