Azure Pack Tenant REST API

I'm trying to use Azure Pack Tenent REST API. I figured out how to work with PowerShell API but using RESTful interface is less documented. 

In Advanced REST Client I get an error: 

There was an error during the request

[chrome socket error]: An SSL protocol error occurred

I've already got a token and I can see all my certificates from WAP in MMC-Certificates console.

What does this error mean? How to fix it?

If I understand it right Admin REST API doesn't care about users' certificates. At least I can use all these methods (https://msdn.microsoft.com/en-us/library/dn448694.aspx) from Administrator interfaces successfully.

BR

Dmitry