I spent several days over the last few weeks researching everything I could on this issue after it started impacting me and I've successfully resolved it and have had no further issues for the last week so I'm comfortable sharing this as a solution to others. Disclaimer: I'm not the guy who figured all this out, I just put it together and am sharing it here.
Problem:
iPhone's lock onto Band 66 from your nearest cell tower. My guess is nearly everyone posting here has a network extender because they get next to no cell phone signal where they are at. Your network extender by default broadcasts on band 13. Your iPhone will not connect to the network extender on band 13 if it is receiving ANY signal, no matter how garbage (including ZERO bars), from a macro tower. This solution will ONLY work if you are positive your LTE Network Extender is functional, i.e. it shows that it is "Open" and "In-Service".
Solution:
1. Go to Verizon support. I did it through the website and just chatted with an agent over text. Hope you get someone knowledgeable and helpful, the first person I had did not have a clue to what a network extender was or how they functioned and it took me well over an hour just to get the thing added to my account. If you get someone like that, I'm not going to lie, leave and come back. It's not worth the headache.
2. Have the customer service representative create an NRB ticket to change your LTE Network Extender to broadcast on Band 66 (preferred) or Band 4 if 66 is not available in your area. Band 4 is a subset of Band 66 and will work with your iPhone based on what I've read. They will need to validate the MAC address of your network extender, require the physical address the Network Extender is located at, and any other information required to validate your account.
3. It takes up to 24 hours for the NRB ticket to be executed. I was never contacted, and I won't lie I never called back to confirm the ticket was executed. I believe the ticket was executed about 6 hours after it was submitted, because that's when my phone went from 0-5 bars and has been working since.
Caveats:
1. I have had to reboot my phone once after leaving the house and coming back when it wouldn't let go of the garbage tower signal. Rebooting my phone immediately connected it back to the LTE Extender.
2. If they push an update to your LTE Extender, supposedly it will revert back to Band 13 and you will have to submit another NBR ticket. This hasn't happened to me yet, I've only read about it on other forums.
This issue was incredibly frustrating to deal with, to the point where I switched phone companies (from Xfinity because they ride Verizon's network and therefore couldn't troubleshoot the actual problem) and was at the point I was about to buy an Android out of anger at Apple. Honestly, I'm still considering buying an Android because this is blatantly an issue with Apple and iOS 14.x, which is where my multi-week fountain of signal issues began. Hopefully this helps someone.
