So this is a dual band router with 2.4ghz and 5ghz wifi.

My problem is when im using the 2.4ghz it is slow, the speed test results for the 2.4ghz is 9Mbps. but when i connect to 5ghz its 85Mbps. 

I tried rebooting and resetting the router but the 2.4ghz wifi is still slow.

This is not normal because i tried using an old router for this and it seems good. 

The reason i bought it because i need the 5ghz wifi because its fast, but still want to retain the 2.4ghz wifi.

Please help if my router is defective