Grey signal bars?

[DesktopDevin]

This was happening to me at home on wifi but it was my firewall on my router that was preventing it from connecting to google servers.

I setup my router to bypass the firewall on the dhcp lease for the phone

Not that this helps in your situation as your are trying to connect on 3/4G but just a tip that I thought I would throw out there on this subject.

[akaguma]

I was perplexed by this problem and stumbled across a very simple solution which has given me nothing but blue bars ever since.
go into SETTINGS
go into DATA USAGE
turn MOBILE DATA to ON
BINGO
as to why this works I have no idea