2 Messages
Modem reboots
My arris sbg8300 reboots weekly. Arris says my upstream qma signal is borderline low, very slightly above 45 on all four channels. I’ve called and once got two people to agree and sent a tech who showed me that all was green. The issue in my view is that the signal drops below 45 causing the router to reboot. Then all looks fine. The reboots occur during the work day creating issues for me. How can the upload signal be improved?
BruceW
Gold Problem Solver
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26K Messages
3 months ago
Arris began saying that upstream QAM signals should be "at least 45 dBmV" several years ago. I don't know why, because it's complete nonsense.
The upstream signal levels are controlled automatically and continuously by Comcast's equipment and do not need to be above 45 dBmV. That's because, as long as upstream levels are not maxed out, what's important is not the level at the modem, it's the level (and quality) of the modem's signal as received at Comcast, which they control by adjusting the modem's transmit level. In fact, many customers have service that works perfectly fine with upstream modem signal levels below 45 dBmV. Some even operate with the upstream below 35 dBmV.
Comcast's signal level ranges are given in https://forums.xfinity.com/conversations/your-home-network/connection-troubleshooting-tips/602da777c5375f08cdea3db9. If Arris' products did not work in those ranges, CableLabs and Comcast would never approve the devices.
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BruceW
Gold Problem Solver
•
26K Messages
3 months ago
Rebooting usually indicates a problem with the link between your gateway and Comcast's network. Network connection problems are often due to poor coax connections or damaged coax cable, usually in or near your home. Running the cable through a surge protector, a defective splitter, or too many splitters can cause signal problems as well. If there is an amplifier in the line make sure it's getting power.
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 (from http://192.168.100.1):
Copy and pasted text is preferred over images. Be aware that, if you post any images, your message will be made Private for a time, as all images must be approved by the Forum Moderators before the messages containing them become generally visible.
If you can't find the problem or you'd rather have Comcast take care of it and an employee does not respond to your message here, 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 (approx $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.
Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.
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