I'm so sorry that you're not able to connect to your Network Extender, or use WiFi Calling. I would be just as concerned over this, as I rely heavily on my phone. 

Can you please tell me when this started happening? Have you tried using WiFi Calling without the phone being in Airplane Mode? Also, do you have a 3G Network Extender, or a 4G Network Extender? 

VanessaS_VZW