Contributor
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65 Messages
Can a modem problem cause issues with cable television?
I spoke with Xfinity tech support this morning because our internet download speed is varying significantly and upload speed has dropped to a tenth of what it should be. Also, our cable television was being slow to respond. After performing some tests, the tech support person suggested that I needed a new Xfinity modem. Our current modem is less than 6 months old, but okay, I'll pick up a new Xfinity modem today. But here's the thing I don't understand:
The tech person told me that a malfunctioning modem can affect the performance of cable television because they share the same coaxial cable.
Is this true? I'm no electrical engineer, but it seems to me that the shared coaxial cable is upstream of both the cable box and modem, i.e., our Xfinity cable box is not routed out of our Xfinity modem, rather the modem and cable box are parallel on the same line. If there's a problem affecting both our modem and cable box, then it's likely the problem upstream of both, the problem being either with the coaxial cable connections outside our house or transmission problems from Xfinity itself, right?
Thanks.
BruceW
Gold Problem Solver
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25.7K Messages
3 years ago
It's possible, but as you suggest, it's more likely that there is a common problem affecting both Internet and TV service. Network connection problems 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 still need help, please post your Internet plan speed and the following information from your modem or gateway:
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 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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EG
Expert
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104.6K Messages
3 years ago
@Anon296804 Just as an FYI.
@BruceW is correct that it is possible, but it is fairly rare. Any device that is connected directly to the Comcast coax cable system can possibly malfunction and inject noise into the cable line / plant and affect other devices. The noise may even reach neighbors devices, and may even affect an entire node. As he stated, it's more likely that something is going on with the line / hardware that is having an effect on the connection quality.
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