I do recall that being taken care of in 1 of my trips back to the store. Phone still lost connection twice after that was supposedly fixed. Hopefully, your's will be working in another couple weeks. Good Luck!!
This happens every time you lose signal. In the beginning shortly after buying mine, I learnt about this problem. Verizon does not see eye to eye with HTC, simply because HTC is trying to leave bloatware out of phone. So in return Verizon has a block in their network that makes it seem like it does not recognize the device. Since band 13 is open communication, they have to allow access.
Now after losing service many times, I researched the correct settings to reprogram the APN settings. This actually gave me better service, but then stopped working. Probably because someone noticed. So now I just go to an area where I know good service exists. I restart my devices and give it five minutes. It will then re-register on the network. Or the prompt about your SIM is ready, will appear. After completing that process it should only take about two more minutes. Then your phone will work again. Unfortunately you will have to do this every time your device loses signal.
The second work around is to put your SIM into another newer device. Like G6, Google Pixel xl, or something equivalent. Once setup is complete, power down an put SIM in your HTC U11. I got tired of Verizon denying to know the truth. Which is sad because I have had FIOS and now wireless for a longtime. I praise them for their great Networks, but this is a pretty low blow. I'm guessing Apple and Samsung must give them a kickback, because HTC 10s and other newer htc devices are not sold in stores anymore. When you ask an associate about htc, their comment is I did not realize we do not carry htc anymore. Really?! Come on Verizon no need to cover up the truth, just let people know you are dissatisfied with HTC for many reasons. But stop the games. And certainly take down the false advertising of bring your own device. Because you are partial. That goes a long way in court! Also the people that are onto you get their posts blocked, no need to make it anymore obvious. I thought about going back to Sprint and Comcast. Just because. I still might...
Below are two links that explain why all HTC U11 have problem, especially the unlocked. Read them, then you will understand. I found a second site that has top ten problems and fixes and says to just get a different phone.
I spent 2 hours at a Verizon store and the couldn't help me, Verizon tech support could not help me, HTC support could not help me. I went home and called Verizon one more time and it turned out the HD calling option was not turned on in my account settings. Once it was activated I could make calls.
Hi Chris, thank you for providing an update. We were sorry to read about these experiences with the U11. We do believe that ensuring HD calling is provisioned at the account level (through My Verizon) and on the device will resolve most of the issues here so we are marking your answer as correct. We will also be updating our internal support resources. Thank you to everyone who posted.
It probably has more to do with Google than Verizon. The pixel is the replacement to the u11. I believe HTC actually manufacturers it. Good ole corporate back scratching. They win, guess I won't buy another HTC, even though I love my U11. Sad!