I had no problem with the link.

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

Websites don't load - troubleshoot and fix error messages

http://kb.mozillazine.org/Error_loading_websites

What do the security warning codes mean

I am not using any of these security products.

i followed through on the tips in the first link, setting no proxy and adding a boolean network condition, no success.

I then started disabling addons, success when stopped HTTPS everywhere. Can load sucessfully now with this disabled, which is not ideal as I would prefer to use this addon.

thanks Fred for your prompt response and ideas.

Contact HTTPS everywhere support. They might be able to help.

You can set an exception for this domain in the HTTPS Everywhere extension to prevent forcing a secure connection.

Note that Firefox comes with a dom.security.https_only_mode pref to block all access via HTTP (this is all or nothing and no exception possible).

Thanks cor-el have done this, works fine, have re-enabled HTTPS everywhere.