Airport Extreme N connected to the broadband modem. The AEN serves DHCP. The network is extended via a new Express N configured as a WDS. The network is full 5Ghz wide band. I have another slower network using an AES and two old Expresses for compatibilty reasons.
It works reasonably well except that some sites are impossible to reach when I am connected on the new Express N with my MBP. Safari shows a blue highlited first part of the address and stalls. At the same time I can acces other sites at normal speed. I can ping the server that i cannot reach and the DNS is resolved properly. The stalling comes just after the resolution of the DNS. It seems to be that the data just don't come to me.
If I move and get connected to the main Extreme N, after several forced reloads, I get to the intended site and the problem goes away.