Apple Watch – No Cellular / Mobile Data (tried everything!)

[offthebandwagon]

Slightly at my wits' end with O2 and the Apple Watch. I have had a mobile data plan for several years, that has never worked consistently. Thought a recent upgrade to the Series 9 Watch might have fixed it, but if anything it's worse. Very rarely works when I'm out for a run without my phone, which is incredibly frustrating, and costing £6/month for nothing.

The Watch knows it has a plan (Says "O2" under plan, and on the iPhone Watch app too), but Status says "No Connection", or "Loading" forever. I do have cellular signal (dots on the Watch face, and can make a call), but no data connection at all (the 'signal' icon is green, but never turns to "4G").

I've seen other resolved posts on here, but never with a concrete solution, can anyone help?

Some useful info:

• I've been through every level of phone and chat Support, turned it off and on a million times, completely reset the watch, removed and reset the plan etc etc. Nothing works.
• It's the same everywhere, even in areas of perfect signal.
• Restarting the Watch very occasionally fixes it, but isn't a practical solution, nor a consistent one.
• My last step was to go in-store, where they basically said I've exhausted all the help they can give! They did try something internal with tech support, but didn't work.

[pgn · Accepted solution]

This should help, @offthebandwagon - Activate Apple Watch Guide 

It contains the collated info off many posts and resolutions. Seems to be very tricky to get the £7 watch tariff to link to your existing phone tariff reliably. Good luck!