I have been experiencing the same issue with Xfinity Connect, but only when trying to access the app on my xfinity wifi. Get rc:1 error. As soon as I turn off wifi and use LTE it works. It also works just fine on my office wifi. Similar problems with cnn.com and trying to download from Galaxy store.
Had Xb3 gateway (Airris TG1682G) for years with no issue, and when I upgraded to Xb6 during plan renewal several months ago the problem started. Traded in it for an Xb7 Gateway and that didn't resolve it. Both are Technicolor. Trying to get an Airris xb6 gateway to see if that will help.
My understanding of networking is limited, but it almost seems like there is a DNS issue, where the wifi is there, but it won't load Xfinity Connect and stumbles on some other sites as well.
Don't know what else to do.
This app is absolutely useless. All the time I see the pop up message:
"Xfinity Connect encountered an error. Pleae try again later."
Any action you take on the mobile app will not sync when you check your email via browser.
It is impossible to manage your emai from the mobile app. There are numerous posts on the app in the google store, but not action(s) have been taken to acknowledge any issues or fixing it. App issues have been around for over a year.
In my case, the connection errors for the Xfinity Connect app were due to a problem with ipv6, and I solved it by turning off ipv6 and just using ipv4.
The Xb6 and Xb7 Gateways are set up for ipv6 but they weren't working properly for me, and there is no option to turn it off. I finally got frustrated enough to buy a separate router, disabled ipv6, and Xfinity Connect app immeditely started working just fine, with no more rc:1 errors.
It seems to be a widespread issue, and Xfinity should either fix the way these gateways access ipv6, or better yet, allow you to disable it in the Gateway admin page.
Anyway, try turning off ipv6 if you can and see if that solves the problem.