Been struggling with this since yesterday. I swap between apple watches frequently and the process to swap cell coverage has been working quite well with Verizon until yesterday. When I try to set up cellular in the Watch app, I can't even get into the Verizon log in screen anymore. Instead I get this small error message on the top corner: "Http:1.1 Service Unavailable". I'm on the latest IOS and Watch OS. Removed cell plan in the app. Nothing has worked so far. Any ideas?