Mesh: issue with certain? Xfinity routers

I have the same problem. Xenon can’t connect to cloud, blinks green Argon connects to the cloud, but Xenon as endpoint through Argon does not connect to the cloud, it blinks green. I have a Comcast Xfinity X1 router, their brand. I’ve tried Xenon as gateway using the ethernet featherwing. That gateway Xenon connects to the cloud, but alas, another Xenon as mesh endpoint does not connect to the cloud with Xenon as gateway. I’m using an iMac OS Mojave, and an iPhone 7S.