I am a retired IT professional who managed data centers for 20 years and have managed websites since mozilla was the king of browsers...
I currently operate a website for a non-profit railroad museum with the domain name "www.spcrr.org". A month or so ago comcast's DNS servers stopped mapping this domain to it's IPv4 address. Comcast based users cannot find our website.
Other DNS servers map this domain correctly. (I have checked 4 different DNS Servers to verify this.). This means that users on comcast based networks cannot locate our website. This is impacting our ability to collect membership dues and sell tickets to our events .
This is not my home router or equipment issue, so don't ask me to reboot my modem again (the prior couple of times didn't fix the problem). We have tested the issue using our membership and found that 100% of our members using comcast cannot browse this website, where all other users can. I can literally browse this website on my phone by turning of my wifi and using cellular data, and then be unable to by turning my local comcast based wifi back on.
Rebooting/reconfiguring my comcast modem/router will not help unless comcast is willing to change the primary and secondary DNS entries to point to a different set of DNS servers then their own.
The router/modem currently points to:
Either Comcast is blocking this website or there is a problem with your DNS propagation. This is not a new problem for comcast. There are numerous reports of this problem on the internet going back to 2014.
The site has DNSSEC configuration errors and won't be accessible using Comcast's or any other DNSSEC DNS until the site's admins correct the errors or the DNSSEC admins make an exception for it. See http://dnsviz.net/d/www.spcrr.org/dnssec/ and https://dnssec-analyzer.verisignlabs.com/www.spcrr.org.