Originally Posted by markc
See if either of these makes a difference...
/etc/nginx/sites-enabled/default:# listen [::]:80 default_server;
/etc/nginx/sites-enabled/default: listen [::]:80 default_server ipv6_only=on;
So I edited /etc/nginx/sites-enabled/default and commented-out the line
listen [::]:80 default_server;
And then restarted nginx. This time it didn't return the error, but said "nginx is running."
I'm guessing this was me telling nginx to stop listening on the IPv6 port?