This is a question for the advanced editor forum, but I'll try to help anyways.
If you have a link (Link 1) and you want to put a restriction on it, IF AND ONLY IF the value is 6, then in the variable restrictions menu, just do your variable name = 6. (Between 6 and 6 is redundant)
Now if we have another link (Link 2) and you also want to put a restriction on it between 4 and 5, that's fine.
If you don't want the first link to appear if your variable value is between 4-5, then open your first link and make sure that "Visible When Inactive" is NOT checked. If you check this box, it will display the link, but you won't be able to click on it. Where if it's unchecked, you can have it not be displayed, and display the other link instead. It's especially useful if you want to include an "initial scene" in a location before giving the reader choices.
Hope this helped!