Yeelight JIAOYUE 650 Offline

Dear Yeelight support, I have an offline issues with 2 Yeelight JIAOYUE 650 lamps.

Model: Yeelight JIAOYUE 650 Surrounding Ambient Lighting LED Ceiling Light
Firmware Version: 1.6.6_0056
Server used : Singapore
MI ID: 1744792246

These 2 lamps goes offline continuosly, then come back online. Everything work perfect till yesterday. Then I have also other yeelight ceiling light (480 and 450) and these are working without problem.
Is there any server issue?
Thank you
Lucas