LAN control doesn't work - Yeelight Color 1S


I’ve got Yeelight Color 1S bulb. I try to control it with UDP packets. I don’t get response from the bulb after sending “M-SEARCH * HTTP/1.1\r\nHOST:\r\nMAN: "ssdp:discover"\r\nST: wifi_bulb” to I suspected that LAN control doesn’t work even though it is turned ON in the Yeelight app. So i disconnected WAN cable from my router and then bulb gone offline, exactly how i thought.

I’ve got the newest firmware and app (i tried to downgrade app to the oldest working version, but with no luck). What is wrong ?

Account number:6319748245
Yeelight Color 1S YLDP13YL

EDIT: My router was the problem. I don’t know exactly why, but i have tested another router and everything is working ok.