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Weird network problem with CAX80 cable modem
My cable went out 3 days ago after 4 months without issue, and no changes on my side. The modem showed a problem with too much power on downstream, so Comcast came today and fixed that. Apparently an upgraded cable line in the neighborhood had more power on the incoming line. The problem is that while the modem doesn't show any errors, it doesn't work properly. I can browse certain sites (google, youtube, netgear) but not most others, such as Amazon. If I can ping the site, I can browse it. The DNS seems to always resolve, but only the sites that resolve to IP6 addresses actually let the ping go through. Not sure if that is a coincidence or not. This happens from multiple laptops, so it is not device specific. I also cannot ping well known IP addresses like 8.8.8.8, which is the Google DNS. The built-in Netgear speedtest has a download speed of 600mb+, and upload of 50mb. Slower than I've gotten (supposed to be 1GB), but still plenty fast. That always runs. I've got Comcast scheduled to come back (two more days), but I am suspicious of Netgear CAX80, because no other neighbors are having problems, and I am the only one with a 3rd party modem. Any ideas would be appreciated. Never seen anything like this before.
Attaching modem diagnostic logs combined in PDF, after Comcast fix (showing everything OK), and before Comcast fix (showing power problem).
I factory reset the modem last night, and after 15 minutes, everything started working. So something must have gotten corrupted in the modem memory/cache of the modem. I am back down again, but this time it seems like a normal Comcast outage. Thanks for the help.
9 Replies
A screen snip is much easier to read (especially for the logs).
have you tried using your own dns provider?
Try a different DNS Server. Here's a few for ipv4. Also remember to change the ipv6 dns server if ipv6 is enabled
CloudFlare 1.1.1.1 and 1.0.0.1
GoogleDNS 8.8.8.8 and 8.8.4.4Yes. In fact, the (win10) laptop connected to the router was configured for Google DNS (8.8.8.8). The first thing I tried was to switch it back to the Comcast DNS. The monitoring software on the laptop (a small app that continuously pings to see if the Internet is connected, and tracks outages) that was failing on the pings to Google (8.8.8.8), Cloudflare (1.1.1.1), and level 3 (4.2.2.2).
I later tried from my primary laptop (win11), and found the same behavior on both. The really weird part is how some IP6 addresses are working. I would think Comcast, but how are the neighbors all working? I'm going to ask Comcast to try one of their modems; perhaps the CAX80 is no longer supported.
and you changed the ipv6 dns address as well?
