Exclamation Point over the Cellular Data Icon + Impaired Data Connectivity

[AC Question]

=====SYMPTOMS=====

Just a few days ago (several weeks after I received the Over the Air (OTA) 5.1 Lollipop Update, my cellular data service icon began showing an exclamation point icon where there would normally be LTE or H.

In using apps, data connectivity is only fleetingly present, but is generally impaired at best.

For example, on the Home screen's Google Now page, I can see updated headlines and articles, but when I click to open the article in Chrome, Chrome tells me "No Data Received."


=====DEVICE CONTEXT=====

Nexus 5
Stock
Lollipop 5.1
Build Number LMY47D



=====REMEDIES I'VE TRIED=====


-Disable / enable Cellular Data


-Remove / re-insert / reseat the existing SIM card


-Fully replaced with brand new SIM card from carrier store (this resolved the issue for about 1 day - the issue returned the next day after I turned WiFi on, connected to a WiFi network, then disconnected from the WiFi network)

-On the phone dialer, enter star#star#4636#star#star > Phone Information > turn cellular radio off / on again

-Wipe Cache Partition

-APN Settings > changing to another APN > reboot

-APN Settings > Menu > Reset to Default > select my carrier APN again > reboot


What is the solution?

 

[B. Diddy]

Welcome to Android Central! Sounds like you've already done a lot to try to figure this out. What did your carrier say about this? Did they only suggest trying a new SIM? Have there been any reports of cell tower outages in your area?