I have been trying to get my cellular activated on my series 4 for weeks. Apple says it’s an account issue with AT&T and AT&T says it’s a hardware issue, which I doubt. The pic is the error message I get. My account only shows one wearable plan so I definitely do not have 2. I got the watch last year on launch day and it activated fine that day. Same phone same watch. I don’t know at what point it disconnected.