Macbook pro internet speed slow - Wireless AC connects at 1300 mbps

I have an Airport Extreme wireless router and 2015 Macbook pro with Wireless AC. The MBP connects to the router at 1300 mbps (TX Rate). My internet speed coming into the router (tested hardwired with the same MBP) is 830 Mbps. Shouldn't I be getting a good throughput on wireless internet on MBP as well? 830 is going into Airport Extreme. Extreme TX rate to MBP is 1300 Mbps.. Yet, I get only around 500 mbps on internet speed test done wirelessly. What am I missing or doing wrong here?

Thanks

Chandra