http://manualzz.com/doc/3550677/tp-link-tl-sg2216-v2-user-guide

let us know how it works out for you

No you cannot cascade range expanders in series. If you want to use multiple range expanders, they all will have to be set to repeat the signal of base wireless router/ Access point. But you can...

I can see that your card isn't new.

tester wrote The problem has been resolved thank you Please write details how did you solve this problem?

Please look in System Preferences - Energy Saver and see what you can find. If any adjustments you make don't make a difference temporarily disconnect one of the drives from the hub and reconnect it...