[WDL-U600AC] Why I can not find my 5GHz router?

There are two types of the WDL-U600AC, FCC and ETSI. Please make sure the 5GHz channel of your router is selected first.
Here is the example of the WDRT-750AC.

If you are using FCC, the WDL-U600AC can find Channels 36, 40, 48, 149, 153, 157, 161, and 165.

If you are using ETSI, the WDL-U600AC can find Channels 36, 40, 44, and 48.