[ubuntu] WiFi speed is OK but did notimprove with new faster router.

I have a Lemu5 with 16.04LTS installed. The Intel AC3160 WiFi card is supposed to go up to 433Mb/s. The most I get is 72Mb/s. Sometimes less that that. My Wireless router is a dual band Buffalo Air Station and also capable of more than 433Mb/s on 5GHZ and 216.7Mb/s on 2.4GHz. Why am I not...