After buying brand new TP-Link RE205 AC750 Universal Wireless Dual Band Range Extender, trying to connect it to my recently purchased new TP -Link Archer C6 AC1200 Dual Band Gigabyte Mesh Router. Only 2.4Ghz 1st band synchs with router using WPS button but not the 5 Ghz 2nd band (LED remains OFF). Tried many times but no success. The Router definitely has got 2 bands working as my laptop shows both the band connections. I have got a 110 MBPS Optical broad band connected to Router using a LAN cable from Modem. Please help. Thanks.