Ceiling light network delay

Hello Yeelight team,
I have about 15 ceiling lights and lamp at home and all is working fine except 3 ceiling light on specific model. What is happening is that these 3 lamps get delay on wifi connection, so this means that to switch on/off I get delay too, even to 2/3 seconds. Restarting lamps will solve the issue, but after a few hours I got again the delay.

Here is a simple ping where is clear the high response time. While I got max 50ms from other lamps:

Reply from byte=32 time=2118ms TTL=254
Request timed out.
Reply from byte=32 time=365ms TTL=254
Reply from byte=32 time=960ms TTL=254
Reply from byte=32 time=66ms TTL=254
Request timed out.
Reply from byte=32 time=2540ms TTL=254

HERE IS THE MODELS WITH DELAY. I cannot anyway explain why I have different firmware version . Yeelight application (European server) show me no update available.
ceiling11 - FW: 2.0.6_0019 - MODEL: YLXD41YL
ceiling11 - FW: 2.0.6_0021 - MODEL: YLXD41YL
ceiling11 - FW: 2.0.6_0023 - MODEL: YLXD41YL

ceiling1 - FW: 2.0.2_0192 - YLXD01YL
ceiling1 - FW: 2.0.2_0192 - YLXD01YL
ceiling1 - FW: 1.5.9_0189 - YLXD12YL

Network and WiFi hostspot is not the root cause, since I have many other Yeelight celiling lights and many other devices like shelly with no issues.

Could you please help me to understand what happen to the model YLXD41YL ?

My ID from Yeelight app: 1744792246

Thank you

It seems I solved my issue myself.
It was an issue related to my hotspot router (Netgear orbi). I enabled the following config:

  • Enable 20/40 MHz Coexistence
  • Channel AUTO (it was fixed to 1)
    And now the 41 “model” are very stable.

Still don’t understand why for the same model I have different firmware.