I have not been able to use my Verizon IPhone 6s Plus in my home on the wifi for about three weeks as the calls all drop. I've been using cellular data and just received a bill from Verizon for data overages. Have reset the modem and phone numerous times and am about ready to switch providers. Oddly, my land line has had no dial tone since Monday. Suggestions?
What modem router/gateway do you have? Can the phone see the network, even if it can't connect? Can it connect, even if it can't get online? Also, can other devices connect to Wifi and get online?
As for your phone, is your phone modem also your internet modem? Have you tried a phone connection directly into the back of the phone modem's Telephone 1 jack?
Also, why are you mentioning dropped calls? You only use Cox for Wifi/internet. Any calls would be through Verizon's cellular connection. Call Verizon to troubleshoot that.
