Ok so show us your settings. Show the message server settings to start with. It works I am using it right now. You have something configured wrong, lets find it.
Do you think Mobile Client helper is still required at this stage? Because I have been going through the forum and see mobile client helper. But it is not in the download page
What IP address are you putting in to the mobile client to connect?
Can you confirm the Android version the tablet is running? According to Google it runs Android 5.1 but regional variations could occur. You can check on the tablet, go to Settings > About (on the tablet settings - not mobile client settings). It needs to be Android 4.3 or above.
MessageServer Service needs to be installed with a 9000+ port. Yes, with +. You set your server with a static IP and then use that IP address to connect your phone. But in the phone you use 9000 port not 9000+.
This is the only thing I found to be a bit misleading in the tutorial but if you did everything else step by step it should work.