I upgraded to AirPort Extreme from the previous router because my Mac would drop the wireless 802.11n connection way too often. I setup AirPort Extreme to connect through PPPoE to my optical fiber cable device. Since then the connection is fast and never drops. On the other hand it seems I cannot access some websites. These include quite a few domains, and also almost all https secured connections. For example, in a website like eBay everything seems to go well until I need to access a secure page over https. Same on Amazon.com and several others. Switching back to the old modem seems to solve the issue, but then I get the old problem of the connection constantly dropping.