unable to connect to .mil on home wifi

I saw another discussion post explaining the same issue I'm having, but there was no actual solution posted to that thread. Whenever i try to access any ".mil" website, I get the popup "This site can't be reached" and the error code "DNS_PROBE_FINISHED_NXDOMAIN". I have tried multiple devices and multiple browsers. When I try on my phone when connected to the wifi, same issue. As soon as i disconnect from the wifi to use cellular and reload the website, it loads instantly. So I know the issue is with the ISP. I am having no other issues with my xfinity home wifi, just .mil sites. Help!