Failed to create session. Please check your connection and try again

Good day,

I've tried to start a session via web page (vuforiachalk.com) and this message appears:

"Failed to create session. Please check your connection and try again".

So, I executed the Network test, but everything turned out to be OK. 

I have tried to start a session from the Android app and with a different laptop and user with the same result.

Is anybody else having the same issue? Thanks in advance.