I've been using a Virgin Superhub 3 as a router for a few years now, port forwarding my pi as a 24/7 web server. It's always worked fine as Virgin gives you a sticky IP as long as you stick to the same MAC, and it's not mission critical for me to change the DNS record if it does change.

I bought the Archer C2300 to replace the Superhub as a router (because it sucks) so the Superhub is now purely a modem, the C2300 is doing all my routing.

Having made the swap and setup a virtual server for the pi though, with the same parameters as I had on the Superhub, I can't get a reliable connection to the pi via the web.

• I can hit the pi from LAN and the web page loads instantly
• I can hit the pi from WAN and the web page take up to 3 mins to load

First, here's what I've setup:

Things I've tried:

• Swap out C2300 for an old Netgear and DMZ the pi - WORKS
• DMZ pi and disable virtual server - SAME RESULT
• Change virtual server details to point at my own PC running a dev copy of the web server - SAME RESULT
• Disable router firewall + antivirus - SAME RESULT
• Disable Upnp - SAME RESULT
• Disable all ALG options - SAME RESULT
• Force Virgin to update my IP address by spoofing MAC - SAME RESULT
• Wait 24 hours with NO changes - SAME RESULT
• Reboot both the Virgin router and the C2300, wait 30 mins - SAME RESULT

I feel like I'm missing something subtle. For the most part, I can always hit the pi's web server and get a response, but either in the request or the response, it's coming back incredibly slowly.

I would appreciate any further suggestions or theories, other than this the router works perfectly and is a breeze to use/setup, but this is a real sticking point for me.