our ssh service currently stopped when we are trying to start the ssh service, it gives us the following error.

'/etc/ssh/sshd_config line 23: directive 'protocol' is not allowed within a match block'.

How can we fix this issue and start the service?

[link to image removed - possible advertising]

I've removed the link to your image because it contains not much more than your attempt to start the service and the error you've already posted. It does contain information about a company and how to contact them, which is potentially advertising. If so, then do not do that and instead contact the LQ site using the Contact Us link at the bottom of the page form.

What you should instead do is post a relevant portion of your sshd_config file around line #23, enough of it to help others to determine what your problem may be. Meanwhile you should not post information that is specific to your server and instead edit out any information that should not be disclosed.

Have you recently changed your configuration? Have you looked at line #23 to determine what the problem may be?