Some people may ask why would they want to turn off LTE and the reason is to have the option to conserve on battery life.
Ive been pretty impressed with the phone so far but the LTE battery life is as typical not stellar. LTE speeds are very nice but there is no option from the phone to turn off LTE and just have HSPA+ to save battery if need be. But I found a way that is really easy to do.
In marketplace under Nokia Collection there is a free app called Network Setup. This app is for people that travel around the world with different carrier network settings based on where they travel.
Nice thing is you can Add your own custom APN settings for HSPA+. The application comes defaulted with At&t LTE settings and AT&t 3g but for what ever reasons the 3g settings don't work.
Once app is downloaded open app "add apn" and use these settings
Connection name: At&t HSPA+
Internet APN settings as follow
Access point name: phone
Yes that's it just the word phone
leave all other setting blank under Internet APN
Under MMS APN
MMS access point name: phone
Proxy address: proxy.mobile.att.net
proxy port: 80
Username: leave blank
Password: leave blank
MMSC address: http://mmsc.cingular.com
Once saved then you can do a before and after internet speed test using a free app called "Bandwidth". I averaged at the time with my test 16-18mbps under LTE and consistent 8-10mbps HSPA+.
Now the LTE logo will still show in the upper left corner next to the reception bars but rest assured you will be using HSPA+.
Hope someone finds this useful.