Has anyone been able to get a stable data connection with CyanogenMod 12.1 on a Nexus 6 with Ting? I'm able to get an unstable 3g connection that cuts in and out about once a minute, and and have never gotten an LTE connection at all. I've tried all the different APN settings I could find, including bringing over the apn config file from stock without any luck.
For anyone else having issues, here is what Fixed it for me.
In Settings > Mobile Networks > Access Point Names, select and edit the "Ting" APN entry.
Remove "IPv6" from the "APN Protocol" field; it should read "IPv4".
Edit "APN Type" and add ",default" to it so that it reads "mms,default".
Save the APN entry and make sure that the radio button next to it is selected. My LTE service connected as soon as I selected the Ting APN, but you may need to reboot