Arrived on site to diagnose a thermostat issues on a goodman 2016 system. Furnace located in upstairs hall way. Client they were having issues connecting to WiFi on there thermostat and app on phone. It stated system would not turn on in heating mode. Found Honeywell T6 pro thermostat had a error code and would not let system turn on. Cleared thermostat as I pulled off 5e wall and reset and system was now operational and heating good. Now tired to set up WiFi on thermostat to be able to connect to phone. Over all found thermostat was not going to connect due to Honeywell connection. Client were interested in replacing with a WiFi nest thermostat. Installed and cycled heating and cooling to ensure system and thermostat is operational. Client cycled off system with phone to ensure WiFi is working on this thermostat. System is no operational upon departure. Would recommend adding surge protectors on high efficient systems to prevent system from gettin damaged from electrical surges and p