FWIW I'm on Firefox as well and the site loaded just fine.

My "go to" answer for these issues is to run the address in virustotal.com, which will tell you about any blacklisting issues the domain may have.

In this case however, and firefox on my machine, I cannot find any issues.

Probably a DNS / dnssec / https configuration? And fwiw, doesn't happen to me.

I wonder why people on HN lately keep thinking network problems are caused by DNSSEC. Nobody uses DNSSEC (certainly this site doesn't). You can almost always assume DNSSEC isn't the problem.

Good to know, thanks! I did once have a domain where DNSSEC was misconfigured and it broke the site for certain types of queries, e.g. example.com would resolve on my ATT router but not on my LTE. And I had no idea why, but I ran a dns checker against it and it said misconfigured DNSSEC. Why don't browsers tell you when (DNSSEC misconfigured) happens?

( Honestly I still don't know why I wanted DNSSEC, but since dnsimple / google domains suggested it in their UX, I figured I should do it. )