I just obtained an ASUS RT-N66U router, which I've flashed with the Tomato firmware. The router is for the most part working fine, but I'm having trouble connecting to Facebook in a consistent way. There's a Macbook Air on the network that always seems to be able to connect, but my Ubuntu laptop can only connect through a VPN.
This seems to me a DNS problem, but a weird one, as it doesn't affect all machines on the network, or all sites, for that matter. I've tried things like changing the DNS server addresses on the router (to Google's and OpenDNS's) and also tried to turn off Ubuntu's local dnsmasq by commenting out
in /etc/NetworkManager/NetworkManager.conf, but without success. I'm not sure what can I try next as I've never had a DNS issue where only one site seems to fail (although twitter seems to be awfully slow without the VPN as well).