I've set up the Netgear MR814 router with a Binatone ADSL modem and things appear to be working , in the sense that dig shows there is a connection to the ISP. However, I can't connect to anywhere and pinging sites generally fails. As soon as I disconnect the router and go back to the modem alone everything works normally again.

I suspect something in the router is misconfigured but I can't think what. Alternatively, could the router and the modem be incompatible in some way?

This is Debian testing, kernel 2.4.24.

I'll reply to my own post, since no one else has. Thanks to information supplied on the Debian mailing list I found that the problem was due to tcp_ecn. Turning this off has made things work properly.

I am 90% sure I have the same problem with you. But when I looked at my tcp_ecn, it is 0. I turned off the ipv6 in modprobe.conf
already!!

Now my applications still sent out ipv6 queries and it take 2 min to time out. My linux box is almost not usable...

I have the same router.
It's a netgear MR814v2.

When i first got the router it would drop connection after a few minutes. Maybe about two or three minutes. I called their support desk. The tech told me to upgrade my firmware. I thought he was just saying that to get rid of me. I upgraded the firmware and haven't had one problem since then.

In windows the router stays up forever and never has to be reset. It's rock solid. In linux it works good with eithernet but I can get my wireless card to work. Linux sucks when it comes to wireless. I am running Mandrake 10.1