try all the possible solution in the link below. http://www.tp-link.com/en/article/?faqid=400

firstly,make sure the modem can be recognized by the pc when it;s plugged directly into the pc secondly, check all the possible settings on the router, update the latest firmware, reset it. check the...

upgrade to the latest firmware and reset the router to factory defaults. see if your modem can be identified. make sure the modem can work properly when plugged into the pc directly.

asraf5285 wrote Max MTU in TL-MR3420 is 1480. Should I, modified it? that depends,generally. it;s required to change the MTU size to be smaller as 1440 or 1400 when some certain websites can not load...

you may log into the tplink web page and check if you have enabled the server under usb settings, storage sharing, and does your usb drive appear on that page?

no idea, :confused:why not contact tplink support ,see if they have any solution,