DNS dropping out intermittently, but Internet connection is good
I have been experiencing "no Internet connection" issues intermittently from many devices on my home network: phones, computers, Xbox. When I looked into it, I find that I can ping IP's on the internet, like 22.214.171.124, but trying a DNS lookup fails. The DNS lookups fail against any DNS server, not just the ones configured on the router.
I know that this is not a real connection issue because some computers can say "no connection" while others are connected via VPN to a work location and have no issues at all.
My guess is that devices are trying to access a URL to determine if the "internet is up", so when the DNS lookup fails, they mark the internet as down.
I had several long sessions with Comcast. First they sent out a replacement router. Then, they sent out a tech. He found several signal issues and changed out some of the splitters and rechecked connections. That did not resolve the problem.
The dropouts can last a few minutes to over an hour.