Thanks for your help as always.
I don't know how to report this, but sometimes it seems that the connection is not done well, then some lag occurs.
To fix it, disconnect and reconnect a few times, now it works properly.
So, sometimes it seems that the connection is made in a way that generates lag ... and this happens in my tests with 2 PCs connected to the same router for testing purposes.
A desktop computer + a laptop.
This happens very occasionally.