Websites not loading

I seem to increasingly see this error message and assumed it was due to my adblcoker ( r/NextDNS ) and usually I navigate away and don't bother with it. My default browser is Safari
I've now experienced this message on a site I want to read and cannot get the site to load. I have tried;

• disabling & quitting NextDNS app
• disabling all browser extensions
• trying alternative browsers (Firefox and Vivaldi)
• connecting via my phone hotspot rather than my home network

Nothing works. I cannot get the site to load. Please only respond if you think you have genuine relevant knowledge about what it happening.