Try nginx -t or systemctl status nginx . It will show you why this happens.
Status of systemctl nginx status was just posted above your reply.
nginx -t output:
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: [emerg] bind() to <ip>:80 failed (99: Cannot assign requested address)
nginx: configuration file /etc/nginx/nginx.conf test failed
This bit: nginx: [emerg] bind() to <ip>:80 failed (99: Cannot assign requested address)
Which is weird.. cause i can connect on the hostname.