You change your router, you have modified your Wi-Fi settings (SSID or password), then you must reset the Wi-Fi settings of the scale.
Reset the Wi-Fi settings of the scale
1. Before to start, make sure your smartphone is connected to the Wi-Fi network you want to install on.
2. Remove one batterie and re-install it.
3. Press the SET button located in the batteries compartment. SET message appears on the screen of the scale.
4. In the app, go in MENU > Set up my devices > Select you HS6 Core scale > Reset Wi-Fi.
5. Enter your Wi-Fi password.
Wi-Fi icon start blinking then is fixed when the connection is successfully established.