T-Mobile HTC One devices usually have the best settings selected by default, however if you feel that your wireless settings are insufficient try this!
HOW TO ADD IPv6 TO SENSE
1. Settings/Mobile Data/Access Point Names/ "3dot Menu"/ New APN
2. Change settings to match these for IPv6
Unlike CM based ROMs there is no option to specify either IPv4 or IPv6 without editing the "build.prop".
3. Edit "build.prop"
[credit goes here (http://forum.xda-developers.com/show....php?t=2115789
Via Root Explorer
1, Open "Root Explorer" and mount R/W.
2, Go to "system" and you will find there is a file name "build.prop".
3, Right click (By holding at the file) and there is menu pop out.
4, Scroll down and select edit in Text Editor.
As you can see there is no "ro.telephony.ipv6_capability= 1" only "ro.telephony.default_network=9". So go ahead and type " ro.telephony.ipv6_capability= 1 " on another line(I put it below "ro.telephony.default_network=9"); save and reboot.
4. After the boot, make your way into the APN settings again and you should see two new input fields: "APN protocol" and "APN roaming protocol"
Make the following changes: "APN Protocol" to "IPv6" and leave "APN Roaming Protocol" at "IPv4"