Cannot access port 80 from remote location but works on local?

You need to enable access to your server on port 80 as it is currently being blocked by iptables.

sudo /sbin/iptables -I INPUT -p tcp -m tcp --dport 80 -j ACCEPT

This will insert the rule into your iptables configuration at the start. Once you have done this and tested that it works then you should save the configuration so that it it is used next time the service starts,

sudo /sbin/service iptables save

this will write the current configuration to /etc/sysconfig/iptables.

If you use CentOS 7 then FirewallD is the right way to go:

firewall-cmd --zone=public --add-port=80/tcp

Verify with your browser that it works, and then:

firewall-cmd --zone=public --add-port=80/tcp --permanent

firewall-cmd --reload

To make changes permanent