@ScottD 

The speed you are getting is based off your link rate, in this case is 144 Mbps.  First make sure the limitation is not due to your hardware.  What type of ethernet ports do your modem and router have?  If they are only 10/100 you won't be able to improve the speed.  Since you have tested with a laptop and a phone that shouldn't be the case.  Next make sure the computer is connected to 5GHz.  If its connected to 2.4GHz the speeds can't be improved.  Lastly make sure the signal where the adapter is located is strong.  Test this with the phone and a speed test in the same location.  

If this all checks out then you would want to check your Duplex setting for your adapter.  You should be able to see this by opening the Device Manager, clicking on network and then the adapter in question.  Click on the Advanced tab and look for Link Speed/Duplex.  I would recommend setting it to Full 1000 and save.  From there restart your PC and then look at the adapter's status again and see if the Link Rate improves.   

  @ScottD 

Hi Scott,  

Sorry its been a while since I have seen a link rate issue.  Co-worker corrected me that Duplex can typically only be set on Ethernet.  WLAN is only auto-negotiate.  Its based on the band your connected to and the RSSI (signal) received.  If you are on 2.4GHz trying switching to 5GHz and if you are already on 5GHz try positioning the adapter as high as possible.  you can even  try a longer USB cable if you need more cord.  The higher the better and interfernce tends to get worse the lower the adapter it. espcially if you bring in a desk or other barriers.  If you are on 5GHz and the signal at the area is good we can possibly look into a RMA for a defective radio, but usually concerns like this are enviroment related.