After switching to an Essential PH-1, I had repeated issues with signal loss and I was unable to get any LTE/4G again without rebooting the phone.
I went through all of the normal stuff, went to the phone vendor and verizon, and eventually found a work around involving two switches in the settings.
Settings > More > Cellular Networks > Preferred Network Type = CDMA + LTE/EvDo
Note that the path and options may vary a bit. This setting restricts the preferred network type to those that Verizon uses. Most others are something else, GSM I think for ATT. With this set, I found that when I did lose LTE signal, it would be able to get the LTE signal back without power cycling phone, but it still took a long while and sometimes needed the wifi shut down to trigger renegotiating the cell signal.
The other switch is in the secret "Developer options" menu. To enable the secret menu:
Settings > About phone. Scroll to the "Build Number" field and tap it a bunch of times. I think it's like 3 or 4 taps opens up developer options. It will tell you when that happens and when you back out of about phone it will be there in settings.
Then you can:
Settings > Developer Options > Cellular Data Always On = Enabled
As noted in the menu, this doesn't mean you are using your cell data connection and eating up bandwidth so it should have no impact on billing. It just keeps the data connection active and tries to reactivate it if it's lost even if you have a wifi connection. This makes switching to cell data faster when you leave wifi since the interface is already up. My guess is that this may have a small impact on battery life in rural low coverage areas but I have noticed no impact on battery life at all. I suspect it's primarily a legacy setting that used to make sense before networks and devices became advanced enough to make it pointless to switch off data. It might also be something network providers want so they can free up IP addresses in DHCP pools, but that sounds fishy.
I found both together solves my issues. With just the Always On setting, it loses signal less often, but still get stuck and as previously mentioned, the inverse will allow it to reestablish without a restart, but it's slow to do so.
Hope this works for others.
Oh, and if any cellular networking experts has some good explanations on what might be behind this work around, I would love to know how it works.
My guess is that Verizon provided phones come with limited network support which automatically corresponds to something similar to setting preferred network type, and that the other issue of taking a long time to rediscover a good signal is something even verizon android phones see. Possibly this is due to the details of the data connection re-establishment code or that LTE is a generation beyond when turning off data was an efficiency win?
Good new / bad news to report. This continued to work until the last update to the 7.1 android security update patch for my PH-1.
After monkeying with it for too long again, I was unable to get to work around the issue with the steps above.
I went ahead and updated to the Oreo beta 2 OPM1.170911.213 and it works much better. There are also way fewer options under preferred network type. Typically I'll use the one labeled 4G/LTE which corresponds to LTE/WCDMA.
The signal bars are not reliable though. In certain areas, the Oreo beta claims an LTE connection with zero bars, but I can still use data, so it's a viable connection. Anyway, it works so I'll stop wasting my time looking for answers.
Unfortunately the Oreo line is still a manual upgrade that is more technical than most end users should attempt. I'm not sure if support can just push the update to you, but it is worth contacting them if you've never done a manual update using android dev tools and you want to get on Oreo to see if it solves a similar problem. It should be GA soon too, so everyone will get oreo without extra steps.