Yesterday I purchased two DIR-850L routers to "refresh" my home network.  For the most part the installation and configuration went fine, but I ended up with a peculiar symptom:
   • When my iPad's WiFi is associated with the DIR-850L Router's SSID and I try to connect to certain domains (e.g. live.com) my iPad browser and email client fail to connect to those domains.  
   
Other Observations
   • If I change my iPad to associate with the second DIR-850L's SSID (set up as an Access Point) I can connect to the problematic domains without issue
   • If I try to connect from my Windows 7 PC, which has a wired connection to the Router, I can connect to the problematic domains without issue
   • I tried connectivity tests from a second iPad Mini associated with the Router's SSID and saw similar problems
   • Other domain connection tests from iPad browser: I can connect to microsoft.com, dlink.com.  I can't connect to apple.com, rogers.com.
   
Hardware: 
   • [Router] D-Link DIR-850L router, ver B1, firmware 2.02
   • [Access Point] D-Link-DIR 850L router, ver B1, firmware 2.01
   • [Gateway] Hitron CGN3 Rogers gateway
Topology:
   • Gateway is set to bridge mode
   • Router's Internet port is connected to Gateway
   • Router's firmware was upgraded to 2.02 during set up
   • Access Point has DHCP shut off and is assigned a fixed IP address (above Router's DHCP range)
   • LAN port of Access Point is connected to LAN port of Router using CAT5 cabling
   • Router and Access Point are assigned different SSIDs
   
I'm stumped as to why this might be happening.  
I'd appreciate any ideas to help me troubleshoot this problem.
Thanks.