Thank you Sbeb89
Your message helped me to debug my connection.
The Firewall has to give full permission to cell.exe, otherwise you connect correctly, but neither waterfall nor sound appeared.
As the connection is set up correctly you start to think the problem is somewhere else (green chain and even with a yellow spark).
In my case, in fact I gave permission when installing the software, but it seems no correct permissions were given.
I had to give full TCP and UDP permission, both on private and public networks, although I guess with public networks it will have been enough.
For those with little idea on the firewall, follow this tutorial (or any similar)
www.tenforums.com/tutorials/70903-add-remove-allowed-apps-through-windows-firewall-windows-10-a.html and in step 3 look for "cell.exe" and grant it full permission. This will do the job.
This could be mentioned more in detail in the user manual, as it could be very useful to avoid the aforementioned problems.
Kind regards,
Stefan