Comcast support is no help at all. They have no idea. After runaround and waiting days for a callback I figured it out on my own.
Here's how I fixed the issue. I had to reactivate the modem on the account (this is a owned modem, not comcast-isssued). You can do this at www.xfinity.com/activate.
Worked perfectly on all remote devices after that.
Hope this helps
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