Not able to connect to Mi Box S via 5Ghz (v10a)

Hello,

Since couple of days, I am not able to connect to 5GHz wifi interface, even though my device (Mi Box S) supports both 2.4GHz and 5GHz connections. 

I have Experia Box v10A model with two superwifi in each floor.

Please help me if you know any setting or work around that can solve this issue, so that my Android box Mi Box S 4k always connects to 5GHz for faster streaming.

Thanks in advance.