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Forum Discussion
CM500-100NAS intermittently slow internet
Hi, Yesterday, if I tried to browse the web, the browser would just hang, but now everything seems to be fine. This happens every now and then. All of the lights on the modem were green. This mode...
You have a ton of correctables and uncorrectables.
Any Criticals, Errors or Warnings seen in the event logs needs to be reviewed and resolved by the ISP. Indicates a signal issue on the ISP line up to the modem.
Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended.
What is the brand and model of the host wifi router connected to the modem?
Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box.
Be sure your using good quality RG6 coax cable up to the modem.
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
Be sure to power OFF the modem for 1 minute then back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Modems/m-p/1530376#M12853
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html
https://highspeed.tips/docsis-events/
Thank you very much for your response.
XFinity customer service was extremely unhelpful - just recommending their modem lol. Need to get a tech out here again.
I'm using CAT5E to connect my modem to router. I'll find/buy a CAT6. I'm using a Deco X20 - a modern WiFi 6 router.
XFinity checked the signal quality up to the modem in the past, but they said it was fine. If I have them come out again, I'll ask if they could check it again. I'm not using any splitters. Both the cable that connects to my modem and the cable running outside appear to be RG6. The line looks like it's in good shape and any connections I can access are secure. Sometimes powering the modem off, waiting, then powering on will fix any issues, but often it doesn't.
I checked out the links you sent. According to that, the correctables/uncorrectables are due to noise. So it seems like the issue has to do with my line or the ISP. Given that the ISP has been out here before and said their signal is fine, I'm suspecting something's bad in the line.
Your response was extremely helpful. Thank you again.
Ya, have tech come out on site and take a look. Have them look at the logs from the modem and info I posted about.
Even though your actual power levels look fine, your logs are indicating they're going in/out of spec.
It could be on other channels as the CM500 is a fairly base model modem anymore.
Once they get the line figured out, I'd be looking at a modem upgrade next. The one you have is fine if you're on a lower-speed plan. I think xfinity has it approved up to 370mbps or around there. So if you have faster speeds, it might be worth checking into upgrading to docsis 3.1. I'd look at their "next gen" approved list
16x4 DOCSIS 3.0. it's a fossil.
What speeds do you pay for?
Might be worth picking up one of the next gen devices if you're in an area that got the mid/high split upgrade.
Again, they'll still need to fix the line issue but the upgrade in upload speeds is kind of nice 🙂
