iPad 2 - iPhone 4s Personal Hotspot slow internet via WiFi

iPad 2 works fine when connecting to my iPhone 4s Personal Hotspot via Bluetooth and the iPad has the bandwidth speed that I would expect over bluetooth. (2 mbs)

When I connect via WiFi I am able to establish a connection and the iPad 2 receives an IP address and DNS addresses, but the internet connection is slower than I would expect or at times seems nonexistent, the server timing out when trying to load a webpage in Safari.

My PC laptop is able to connect to and load web content okay when using the iPhone 4s' Personal Hotspot, although it is slower than normal.

All along my iPhone 4s has a consistent connection , downloading at 5-6 mbs.

Also, the iPad 2 works fine on regular WiFi (at work and at home).

I've contacted AT&T and they instructed me to reset the devices, which i did, but this has not resolved the issue. Any thoughts?