I implemented the solution planned some posts ago... It seems to work well!
Now all commands arrive to the server application!
However initially I've seen that 2 commands very near in time were not executed... I was really going crazy!!! Luckily, I noticed that there was also a problem in the server application: if two commands arrive at the same time, the function connected to the signal readyRead() is called only one time, and so executes only the first command.
To solve this problem, I've made a control over the socket buffer (based on the method bytesAvailable()): if at the end of the first command there are other bytes in the buffer, I call the function to read commands another time! In this way I'm sure to execute all the commands received in the buffer!
I don't know if this is the best solution... Anyway, at the moment It works!!!
If at debug time I discover some problems, surely I let you know!
Thanks for all contributions! If any of you needs some more deep explanations for this problem, ask!

See you all!
Alex