Comcast DNS servers are dropping constantly (18.104.22.168 and 22.214.171.124) ... Revisited 2020
This post references a previous question post from 2013 of the same subject title minus the "... Revisited 2020". I tried to post new to that thread but apparently that is not possible, or not easy through Xfinity's interface (I'm a little new to RSS feeds). There may be a proper way to reference previous feeds/postings in a new posting but apologies I do not know that procedure.
It would appear that this issue is happening again, for my locality at least. This involves the same DNS server IP addresses as in the previous post and in the subject of this post, normally set automatically from configuration info sent from Xfinity servers. This time it is early 2020. This started happening recently, in the last few months, may have started end of 2019 but I don't recall for sure. It happened again this morning. I will have a fully-functioning internet connection for hours when suddenly the browser is unable to resolve any hostnames. Then I reboot my MG-7550 cable modem/router/access point over and over every minute or so, each time apparently connecting successfully over the Ethernet via DHCP info but not seeing the DNS server IP addresses get populated from the Xfinity server information. After about 5-10 minutes, I get the DNS server info and can resolve hostnames again. This happens every week or two any more.
Given that I retain the Ethernet connection but lose the hosname resolution ability I have trouble believing that ths is solely a connection/wiring issue. Otherwise why would the Ethernet connection be successful but the DNS server info not? It really seems like the DNS server(s) are being rebooted for whatever reason. It doesn't show up in the Xfinity online outage indicator as an outage in the area. No outages are reported. I just chatted with Xfinity support and was basically teaching them the basics of Ethernet connections and DNS servers.
One thing about the previous occurrence of this type of issue in this area (central Pennsylvania locale specifically in this case), there was a bunch of talk about ping activity being moderated by the Xfinity servers. However, I didn't get the impression that the person who reported the original occurrence was basing the report solely on the ping responses, rather the problem that triggered the issue was more likely similar to mine, sudden cessation of hostname resolution for 5-10 minutes. My impression was that the ping utility was just being used as a tool to diagnose the issue.
FWIW, I am an electrical/software engineer with many years of experience designing Ethernet circuitry for single-board computers and subsequently programming the embedded interface, in "Internet of Things" sorts of applications. I may still be missing something here, but I am just giving my credentials for reader reference.