If you get this message, you have to change your "listen" statement from
listen 94.229.77.82:80;
listen [2a01:348:226:dead:beef:dead:beef:dead]:80;
to
listen 94.229.77.82:443;
listen [2a01:348:226:dead:beef:dead:beef:dead]:443 ipv6only=on;
For some add reason the first statement (without "ipv6only") was working for me for some time... odd.