I have not been able to get my phone to connect to LTE for the last several weeks. Last month I was in Japan for 2 weeks and while I was there I had a data-only Japanese SIM card in my phone from the Japanese carrier bmobile. To use the SIM card, I had to install a profile, which I deleted when I returned to the US and re-inserted my Verizon SIM. Since then, however, my phone has not been able to connect to LTE. It alternates between 1x, 3G, and No Service when I am not on WiFi. Occasionally, LTE will show up in the service bar, but when I open Safari and try to load anything, I get a "Could not activate cellular data network" error message popping up, meaning the LTE isn't actually connecting.

I have already been to a Verizon store to have the SIM replaced. Tried resetting Network Settings dozens of times. Also tried resetting phone to factory settings and restoring from iCloud as well as resetting and restoring from iTunes. I've spent hours talking to Verizon support, Apple support, and scouring forums across the web about this issue. Verizon and Apple have been useless. After like 2 hours on the phone troubleshooting, they "escalated" it to their "highest support team" and the best they could suggest is that I use Wi-Fi calling *eyes roll all the way to the back of my head*. Apple's solution is to reset to factory. It seems to me that this is a known issue (have found several threads with people describing this same problem) but there are few working solutions beyond restoring the phone to factory settings and starting from scratch (ie without restoring from backup). Incredibly frustrating that neither Apple nor Verizon has done anything to make this easier to resolve.

This thread is the closest I've gotten to finding a solution/also exactly describes my problem: https://forums.whirlpool.net.au/archive/2690435 

Unfortunately, when I try to install a profile using the Apple Configurator 2 method described, the profile fails to install. I am at my wits end. I can live with just 3G service for now, and I've disabled LTE on my phone so it doesn't even attempt to connect to that (because when it does it ends up getting stuck on No Service and I have to restart the phone).

Has anyone experienced this issue and found a solution besides factory resetting with no backup? I'm not really willing to do that because I don't feel that I should have to lose all my data beyond photos/contacts to fix what I think is a relatively simple issue (messed up carrier/APN settings). Would appreciate any insights.