Galaxy S3 AT&T 16GB rooted but never use the root nor made modifications im running Jelly Bean 4.1.1.

Below is listed two APNs that I use to get strictly 3G/4G network because I want to save my battery on my AT&T Galaxy S3 running Jelly Bean 4.1.1. I don't want my phone looking for nor connecting to the LTE network. But I run into the problem of constently losing signal randomly while running on either of the 3G/4G APNs I have manually set. After I lose signal my phone reconnects within two minutes back on to the 3G/4G network which is what I want it to do. But I dont want to have the problem of constently losing signal. I never lose signal when I have my APN set to the orignal APN that came already set on my phone which is called "ATT Phone".

When I do lose signal its not like im in a poor signal area. I have an iPhone 4S aswell and I never lose signal while I do on the Galaxy S3. The iPhone is on AT&T as well.
I live in Plano TX which is an LTE area

Are there other APNs I can try for AT&T? Do I have something set wrong listed on the two APNs listed below?

Any help would be appreciated,
Thanks

3G APN -
APN: wap.cingular
Proxy: Not Set
Port: Not Set
Username: wap@cingulargprs.com
Password: CINGULAR1
Server: Not Set
MMSC: http://mmsc.cingular.com
MMS Proxy: Not set
MMS port: 80
MCC: 310
MNC: 410
Authentication type: Not Set
APN type: Not Set
Bearer: Unspecified

3G APN 2 -
APN: wap.cingular
Proxy: Not Set
Port: Not Set
Username: Not Set
Password: Not Set
Server: Not Set
MMSC: Not Set
MMS Proxy: Not set
MMS port: Not Set
MCC: 310
MNC: 410
Authentication type: Not Set
APN type: Not Set
Bearer: Unspecified