Atheros WLAN 5G not available

Hello,
I have the following problem,
I have a TPLINK WDR3600
after a firstboot reset ,I have only one wireless (Generic 802.11bgn) visible.. the 5 G (Atheros) is unfortunately not available. Unfortunately I have little idea what went wrong.
Hope here for my problem to find a solution.
Thanks a lot

Marcell