I've recently installed ISPConfig and configured the server in line with the "Perfect Server" tutorial held on HowToForge - http://www.howtoforge.com/perfect-server-debian-wheezy-nginx-bind-dovecot-ispconfig-3. I've used this tutorial before on different VPS's and I've never had this issue before.

When I type in the IP address of the server, it spends its time working out the address and then Firefox gives the message:



I've also followed this guide to sort out the firewall: https://www.linode.com/docs/security/securing-your-server/. I added 8080 to the end of the example, so this is what it looks like for me now:

  *filter

  #  Allow all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
  -A INPUT -i lo -j ACCEPT
  -A INPUT -d 127.0.0.0/8 -j REJECT

  #  Accept all established inbound connections
  -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

  #  Allow all outbound traffic - you can modify this to only allow certain traffic
  -A OUTPUT -j ACCEPT

  #  Allow HTTP and HTTPS connections from anywhere (the normal ports for websites and SSL).
  -A INPUT -p tcp --dport 80 -j ACCEPT
  -A INPUT -p tcp --dport 443 -j ACCEPT
  -A INPUT -p tcp --dport 8080 -j ACCEPT

  #  Allow SSH connections
  #
  #  The -dport number should be the same port number you set in sshd_config
  #
  -A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT

  #  Allow ping
  -A INPUT -p icmp -j ACCEPT

  #  Log iptables denied calls
  -A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7

  #  Drop all other inbound - default deny unless explicitly allowed policy
  -A INPUT -j DROP
  -A FORWARD -j DROP

  COMMIT

I've restarted iptables, and I've restarted the server, but nothing seems to work. Can someone please advise?

Have you checked your current iptables rules via something like iptables -L -n to verify they actually match what's in your config?