ESP8266 Stops Working if I don't provide Wifi during specifc step.

Dear all.

To test the WiFi connection I'm sharing the WiFi of my cellphone.

If I stop the WiFi sharing during the command below, the ESP8266 stops working.
It only works if I do a hardware reset.

if(client->POST(urlCal, host, payload))
  { RetornoPost = client->getResponseBody(); }

Tks and Best Regards
Bruno Arita