Yeelight keep disconnect please help

Hi. I’ve brought both Yeelight Bulb and Yeelight Strip (Yeelight smart light color 2). I can connect using hotspot, has switched to us server, and google home is fine. But I think I’ve got some problem with the Yeelight bulb and strip. If I turn both Yeelight on, not long after that, one of them which I connect the latest will disconnect and turn off by itself. In my case, I connect and turn both yeelight bulb and strip on. But not long after that, my Yeelight bulb stays on, but suddenly my Yeelight strip turns off and disconnect by itself. Anybody knows why is it happening? And is there any advice?

If you are unable to make the connection, then check the below reason and fix the problems.
Simply reset and re-connect
May be WiFi router doesn’t set appropriately?
The phone OS version is not compatible to the bulb
WiFi router security level is high
Product quality issue

If I have a problem with one of those, why I still be able to connect to the Yeelight bulb and strip?