For this issue, you can refer to the following information:
1. Please place the Xiaomi Body Composition Scale S400 next to the gateway device, not more than 10 meters apart;
2. Please check whether the gateway is on and online;
3. Please check whether the gateway device has been updated to the latest firmware version;
4. Please check whether the gateway is bound to the same Xiaomi Account with the Xiaomi Body Composition Scale S400;
5. Try to restart the gateway, unplug the power plug of the gateway and plug it back in.