My wife & I have the same "LG Phoenix 2" (LG-K371) Android GSM phones running version 7.0/3.10.49/NRD90U/K37120k. These are AT&T "Go" phones made to run specifically on the ATT network, and our provider is Consumer Cellular, which uses the ATT network. Our phones worked perfectly till about noon on 9/26/17, after which both phones failed to deliver HTTPS content over the mobile network (Firefox reports "Secure Connection Failed" and Chrome delivers ERR_EMPTY_RESPONSE). Non-secure (HTTP) content continued working over mobile. Both HTTPS and HTTP work fine over WiFi, and neither phone applied any updates at the time of the failure, so this is not a phone or browser issue, but some sort of mobile network HTTPS proxy server issue with Consumer Cellular. We are in the Minneapolis area. Is anyone else experiencing this?