Before I added a wireless router (D-Link WBR-1310) to my network, my home LAN setup was configured as such:
(internet) <--> DSL modem <--> Ubuntu 6.04 webserver/gateway/router <--> LAN PCs
After the addition of the wireless router, I removed the Ubuntu server's routing capabilities, and added port-forwarding in the router to the webserver's IP address. The network is currently configured as such:
(internet) <--> DSL modem <--> wireless router ---> LAN PCs and Ubuntu 6.04 webserver
The problem that arose since this change, is that LAN PCs can no longer access the webserver by registered domain name or ISP-assigned IP address (188.8.131.52), only by the webserver's LAN IP address. I have multiple domains hosted off the webserver, and accessing any of them from a LAN PC results in a timeout error in the web client browser.
After some digging around, I installed WireShark on the webserver, and captured packet data coming from a LAN PC. The first image below is a 'success' hit on the webserver's IP address. The second image is a 'failure' timeout on one of the registered domain names/ISP-assigned IP address.
My iptables ruleset isn't actively blocking syn/ack/rst flags in packets, so I am unsure what I can do to resolve this problem. I guess I should note too that if I accept all incoming traffic in iptables, the problems listed above are not resolved.