Could it be you've bought the US Nexus 5?

There's two versions.

North America:
GSM: 850/900/1800/1900 MHz
CDMA: Band Class: 0/1/10
WCDMA: Bands: 1/2/4/5/6/8/19
LTE: Bands: 1/2/4/5/17/19/25/26/41

Rest of World:
GSM: 850/900/1800/1900 MHz
WCDMA: Bands: 1/2/4/5/6/8
LTE: Bands: 1/3/5/7/8/20


In the UK (and Europe) we generally use 3/7/20 which is what the Jolla supports.