I have a digi gigabit internet connection and using wifi 5 Ghz, the download speed is very slow, approximatelly 200 Mbps but the upload speed is the given maximum 300 Mbps. The router settings: Mode: 802.11a/n/ac mixed, channel with : 80Mhz, channel: 48, trnasmit power: high. What could be the problem? I tried on wire, it works fine with 600-700 Mbps.