I ask one of my friends who comprehend computer well. Then I know, the difference of USB 1.1 and 2.0 is not only reflected in the transmission rate, but also the voltage and current. In one word, USB 2.0 extension cable is more strict to the aboving parameters and the material of cable. If the quality doee not match the standard, USB 2.0 extension cable will automatically downgraded to USB 1.1 mode. The questions you meet that the computer said "does not recognize the device" rather than “high-speed device insert into a low-speed hub “, it means the question is more serious than description down to USB 1.1.USB 2.0 extension cable couldn't work as normal. You can find some low power requirements of equipment to try, such as a mouse, handle, U disk, etc., if no problem appears when this type of device connected but it doesn't work like the mobile hard disk and power equipment insert, it explains that large power loss of USB 2.0 extension cable, we can only directly connect this type of device to the motherboard.