Shell access to a Linux server may cause the screen to freeze.
You might think that the shell hung up. But most of the time the problem is just an incorrect key combination.
If you accidentally press [Ctrl-S] , then this signal for a Linux computer means that the remote station is ordering you to stop because the data that has been received so far still needs to be processed. He therefore stops any output.
Only with the key combination [Ctrl - Q] this wait state is canceled.
For those who are particularly interested: This is the same procedure that is used in the case of modems under the heading of software handshaking (XON / XOFF).