Refreshing the page makes it work again.

The only thing I've been able to find relating to it is: https://askubuntu.com/questions/1037501/firefox-fails-to-securely-connect-to-google-services-at-random-times-ubuntu-16

For instance, this one just did it for me: https://forums.theregister.co.uk/forum/1/2018/05/18/network_roundup_17_may_2018/

Anyone else experiencing this? Trying to figure out if it is something network related/firefox related/ssl related