Model : TL-WDN3800

Hardware Version : Not Clear

Firmware Version :

ISP :

Hello,
in October 2015 I bought the wifi PCIe card TL-WDN3800.
Initially I was using it only to connect to the internet from my desktop pc and I didn't find any issue because my internet connection is 150mbps.
Now I bought a laptop and I would like to transfer file between the two. Doing so I realized that the card speed is capped at 150mpbs. I tried to connect the desktop with a cable to the router and I can achieve the 500mbps promised by the router, therefore the bottleneck appears to be the PCIe card.
I tried to position the desktop very near to the router but the speed remains the same. I updated the drivers and increased the buffers to 512 but the result is always 150mbps. Do you have any suggestion to reach the 300mbps advertised?

I'm on windows10 64bit and the router is not farer than 15 meters from the card. With other wifi devices the router can easily manage 500mbps.