Unable to detect smart switch

Recently i changed my router to TP link AC3000 (AX3000 4-Stream Wi-Fi 6 Router) but after that i cant detect the sonoff smart switch using the quick pair and also compatible mode way.
Any setting i need to change at the router ?

Please make sure that you are connected to 2.4 GHz WiFi, since your router supports 2.4, 5 and 6.

Try to set different wifi name (SSID) for 2.4Ghz and 5Ghz wifi

done but still having same problem