"NO" symbol icon, problem since 4.1.2 update

[brentj]

Since the 4.1.2 update, my GN2 has more easily lost connection to the Sprint network. Not only that, but sometimes when it loses connection, the "NO" symbol shows up in my notification bar, and then my phone will not connect again to Sprint (even if I travel miles within the metropolitan area), until I either restart my phone, or switch to airplane mode and then back again. See the screenshot below of the "NO" symbol showing up in my notification bar. Pages 27-29 of the User Guide list icons that can appear in the status bar, and the "NO" symbol is not listed there. Anyone else having this problem? I did a factory reset of my phone (which has never been rooted) and the problem still exists. Any suggestions? Thanks in advance for any assistance!

 

[brentj]

I took my phone into a Sprint center to get it checked out. The tech called me to pick it up, told me that he thinks the problem was caused by Sprint's Connection Optimizer being turned on. I'm pretty sure I had turned it off, but he said that new OTA updates generally turn it back on. He said that when they set up new phones for customers, they always turn it off. So far the problems have not recurred, but it's only been two days. I'll be sure to check this setting after every future OTA update. Settings > More Settings > Mobile Networks > Connections optimizer