Getting high uncorrectable codewords

... very high uncorrectable codewords ...

The two channels with the high error counts also have out-of-spec (too low) SNR. Network connection problems like this are often due to poor coax connections or damaged coax cable, usually in or near your home.

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If you can't find the problem or you'd rather have Comcast take care of it, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. It's not likely they can fix the problem remotely. If not, insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit ($70-$100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

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Hello @RJFader and thank you for bringing your concern regarding certain signals on your modem to our attention here at the Xfinity Forums. Were you able to follow the great tips and information provided by @BruceW in this thread so far to troubleshoot the issue further or reach out to our Xfinity Support team? If not and you are still experiencing connectivity issues our Forum specialists would be glad to help!

Hey all, at this point I'm going to need a tech to come out I think. @BruceW definitely had good tips and information, so I appreciate that.