AppleWatch Siri say no response at first time, but ok on second and subsequent times

AppleWatch Siri say no response at first time, but ok on second and subsequent times. But on my Iphone that is no problem.

I used a computer on the same LAN and found that my iPhone would periodically send mdns, but my Apple Watch would only send it when using Siri.

Apple Watch prohibits the Home background from send mdns in order to save power?

Another problem is when I open home app on AppleWatch, all of my devices show no response, that need 10-15 second to recover.