Powershell Remoting fails with 502 error from server
502 usually results from an intermediate gateway/proxy unable to understand server’s response.
If however, you don't expect a gateway or proxy to sit between your client and server, this error may result from a misconfigured proxy settings on your client box.
To view, proxy settings, run the following on your client box:
netsh winhttp show proxy
The problem should go away once you reset your client side proxy configuraiton
netsh winhttp reset proxy