It appears that I can make calls on the extender now. However, it still gets kicked intermittently. Seems to be getting better.
iOS version: 10.0.2 (14A456)
Modem Firmware: 2.30.00
I'm having this problem now. I got an iPhone 7 last Friday, and immediately started having problems with *all* of my devices intermittently connecting to the extender. I really thought it was just a problem with the extender (it didn't even occur to me that the iPhone may be involved), but after a week of troubleshooting with Verizon, it's very obvious this is a problem with the iPhone. If I turn off the iPhone, the extender works fine. Once I turn it on, within a few hours my other devices start having problems connecting (and saying connected) to the extender.
Has everyone looked at their LTE extender logs? You can view these on your LTE Extender web admin page. You'll need to find the IP address of your 4G extender first. You can do that by cycling through the screens on the front of the network extender.
Type that address in a web browser. When prompted, the default password for the extender is LteFemt0 (that's a zero at the end).
Then go to About->Status and Alerts. On that page, under Status Details, there should be something that says System Detail History. Click on that and look for messages saying the extender is "Not In-Service."
I had the same problem. Iphone 6 worked, 7 mostly didn't, but occasionally did. It turns out there's a setting on the phone that has it preferentially choose the terrible 4G distant cell tower connection rather than the strong 3G network extender. Reconfiguring the phone setting fixed it. Turn HD Voice On/Off - 3G Network Extender - Smartphone | Verizon Wireless