How do I resolve 501: Method Not Implemented in MRD for OSX El Captain?
After a lot of trial &amp; error, I figured out the most logical assumptions &amp; got it to work. It goes like this (in-case anyone else finds the same problem &amp; is looking forward to an answer):


Determine the host gate way
Physically access the computer
Open up Windows Services (if host is Windows)
In Services, look for Remote Desktop Services
In Remote Desktop Services, click Properties &amp; drop down to Automatic if not already
Restart the Machine (Optional)


Try again with your MBP, and with Wireless connection, you need not set any additional GW info on RDP Client. Food for thought is - this could be one possible way out of many other circumstances you run into. Make sure RDP services aren't disabled on the GW which's suppose to distribute the connection packets &amp; route it the way it should. 

Let me know in case I could additionally help with something entirely different if the circumstances are different &amp; RDP services are already not disabled.