One of the main issues that arrived early on with the Pixel and Pixel XL was an issue with Band 4 LTE which meant mediocre to terrible 4G reception for some users. Bugs like these are normal early on and are the sacrifices early adopters are generally willing to make in order to use the latest handsets. Many users who were encountering the reception issues are reporting that the issues are gone after they updated their device to Android 7.1.1. If you have found your device to have spotty issues in places that the 1700MHz spectrum is used you should go grab the update and check your connection afterwards.
via Google Product Forum