While working on one of clients server I came across one of  the errors in Apache error logs

root@hosting [/usr/local/apache/logs]# tail -n 10 error_log
[Thu Jul 07 23:28:49.791175 2016] [core:warn] [pid 1845] (113)No route to host: AH00056: connect to listener on [::]:443

The error was due to basically iptables blocking

I went ahead and flushed iptables to get this issue resolved using below command

# iptables -F
# iptables -X
# iptables -t nat -F
# iptables -t nat -X
# iptables -t mangle -F
# iptables -t mangle -X#

/etc/init.d/iptables save
# /etc/init.d/iptables restart

I can see there are no more such errors now in error logs 🙂