Support Forum

There are, I believe, several WP plugins that will allow you to ban users in a variety of ways so I would hunt those down.
If you just want to temporarily ban someone from just the forum then one way is to create a special user group for such members and attach that to a permission set with 'no access' and then when you assign those to forums members in that user group will not be able to see them.

Individuals using the forum only – then use the user group method I described above.
SP does not perform IP banning and it is not a great way of banning users anyway.

We disagree. Neither IP or username banning are really very effective against any user determined to leave his mark.

But you are clearly missing the point regarding the user group setup.
Create a NEW user group. Call it, for example, 'banned'. Add any member you wish to ban into that new user group.

Go to group and forum management and add the new user group to them with the permission set of 'No Access'.

Do this and you have stopped any users in that group from seeing forums but they can still see the rest of the site.

This will target specific members just like user name banning. It does not, in the same way as username or IP banning, stop them from signing up with a new account.

there are other plugins for wp that do banning… wp-ban for example can do what you want…

users are the pervue of wp… we are just a plugin and piggy back on the user base of wp…

And – I have actually told you erxactly how – at least twice now.