GL-AR300M - 2nd USB drive is not being recognised

My router is working fine with one USB 3 USB DRIVE.
Trying to add 2nd usb 2.0 disk using a USB hub. I tried with USB 2.0 and 3.0 hubs.

When old one (USB 3.0) is connected to hub, it works well. When new disk (USB 2.0) is connected both disks are not recognised.

I have 2 amps power adopter connected, with 2 disk router takes max 1.0 amp. There is no power crunch.

What could be the issue?

Is the Hub powered?

AR300M, if I recall, is current limited to 500mA, so unpowered hub, along with bus powered drives, you might be exceeding the power budget