Who is your ISP in Iran?
If possible, test the SIM card on your phone or a different modem.
Try to find the log from C:\Program Files\TP-LINK\TP-LINK 3G Client. Save the log. Send it to support.ir@tp-link.com with your problem. :)

you can try these settings
> control panel > device manager > network adapters > right click hit properties > Power Management tab > uncheck computer can turn off this device.

If thats already unchecked you might need to go into Control panel > power > (whatever setting your using) hit edit plan settings > hit advanced settings > then USB settings > selective suspend setting > make sure its disabled.

I had this problem recently, it took me quite a while to figure this one out. In the end it helped a bit but my problem was I had an outdated driver.

may be u can try Internet connection in the restart again

You should try to off your modem and on after a pause. Then your internet connection will reconnect easily.

This is drivers problem///The way to check also power control in panel is not bad///