Question [Q] New notification bar icon

Mornin' folks,
I just unlocked and rooted my m7. Still on stock ROM. There's a new icon on my notify bar next to the 4G icon. It looks like a stylized 'N'. It won't go away and I can't find any reference to it. Anybody know what this is?
HTC One Silver, unlocked with TWRP 2.7 and rooted, stock ROM.