I tried the RDP sandbox today and the connection to the IBM i system iseriesd.demos.ibm.com doesn't work.
I get the following error, the system is running, I can access it with a 5250 session. It is the RSE connection that doesn't work.
An unknown error occurred connecting to ISERIESD.DEMOS.IBM.COM. Check if you have connection to the host. If the connection is not broken, check that TCP/IP is configured correctly on the local machine and all host servers are started on ISERIESD.DEMOS.IBM.COM.