Extender does not detect 5G internet connection from primary router. 5G signal LED is switched off and unable to scan 5G network from TPlink admin page also. However it detects and connects successfully with 2.4GHz channel. This is strange as all other devices like laptop, phones able to connect on 5G primary network connection of AIrtel broadband. Pls suggest solution. I have tried all basic troubleshootings, factory reset extender, tried with WPS, manual configuration and also 5G without security does not work. 

 RE305 AC1200 Dual-Band Wi-Fi Range Extender