This is from a Nexus 6P forum. Sound familiar???
Comment
#70 on issue 232089 by*tcha..
@gmail.com: Android 7.1.1 Nexus 6P*
T-mobile network interruption bug
https://code.google.com/p/android/issues/detail?id=232089
This is still a problem on N4F26O, with the supplied baseband (03.78), and
for me at least it manifests in the exact same way; immediate modem reset
when CA kicks in with Band 2 as the PCC.
Steps to reproduce
Camp on a T-Mobile site with carrier aggregation (CA) and at least Bands 2
and 4.* Wait for device to camp on Band 2, then start a large download.
Frequency
100% of the time when the device is camping on Band 2 on a CA enabled site.
Expected output
I expect my LTE modem not to crash/reset.
Current output
Modem resets, losing all network connectivity, then re-establishes a
connection.* Occasionally it will not re-establish and a cycle of airplane
mode or even a full reboot is required.