Public xfinitywifi/XFINITY hotspots does not like my phone

I am an eligible Xfinity Internet subscriber, so I do have access to Xfinity WiFi hotspots nationwide.

Except it often doesn't work on my mobile phone (Google Pixel 1 running Android 10). At the same time in the same spot, my laptop is working fine with the same hotspot, but on the phone, I very frequently get this "Access temporarily denied on this device" error.

(Here was a screenshot -- for some reason it gets removed. Here is the link to the screenshot of an error message I get: https://photos.app.goo.gl/z19yGfvie1482mjw8)

Now, it suggests retrying again in a few minutes and view FAQ. I did all of that and more, in particular:

 - added a separate (secondary) user to use its credentials (login/password);

 - removed the mobile phone from the list of "my devices" here;

And yet I still have two problems:
1. it very frequently asks me again for login/password (meaning that the Automatic Sign-In described here is not working);
2. it often gives me the above "Access temporarily denied on this device" error.

Feels like my device's MAC in some sort of a deny-list, or something. Sometimes it works though.

Please help