@Marc779 What's the model, hardware and firmware version of your Deco system? How about the hardware and firmware version of your HS110?

@mswsnc You may also refer to this video tutorial. TP-LINK® ’s HS200 Smart WiFi Light Switch Setup Tutorial If it's still unclear for you, please seek guidance from an electrician.

@yman1437 Is it possible for you to bypass the GFCI and rewire the switch for testing purposes? If the switch can be powered on (led indicator turns on) when connected without the GFCI, could you...

@dhjdhj The login status of the account can be maintained and will not be signed out when there is no Internet connection.

@TFitzpatri8 Thank you for your clarification. To assist with this problem, a support ticket will be sent to your registered email, kindly check your inbox later and confirm.

@mswsnc For detailed guidance on wiring and installation issues concerning the HS200, please refer to the information provided in this FAQ. How to install HS200 to your electrical line