how to make web pages accessible all the time

I can only access php web pages on my redhat 7 server, after I run iptables -F on server. Then, after a while, I need to run iptables -F again to access web pages. I tried to stop iptables service and saved, but it only works for a while. Once I cannot access to web pages, I need to run iptables -F again. I was wondering how to make my web pages accessible all the time.