Hello. It is not the solution to our problem.
Sap and SQL services are ok, so they don't need to be restarted.
TCP/IP runs well too.
The solution is in the answer down here (Avinish Sharma) and up here (Juric Tihomir)
Thanks for your support, I underline the correct answers so that users can understand immediately what they need to do to solve the problem.
Daniele