|If you've checked all the above posts and still no joy, take a look at your connextant again. You said:|
I have configured the lan settings on the conexant as follows: IP 192.168.1.1, mask 255.255.255.0, gateway 192.168.1.1
Now I admit, I'm not familiar with conextant equipment but I know the D-Link router I have at home, I don't put in a gateway address on the LAN interface since it does it's routing internally. You have your LAN interface pointing at itself for Gateway according to what you posted. With a setup like that, your clients will never get beyond that interface to the external one (ergo, to the web).
I'd wager removing the gateway from the LAN interface of your connextant, or changing it to the IP of your external inferface (again, shouldn't be necessary as the NAT/Router should handle the routing internally between interfaces) would fix the problem as well.