I see your post has been up for some time with no response. I did some looking to see what we may have available for you through <a href://my.f5.com>MyF5</a> and found https://my.f5.com/manage/s/article/K61064431 which does give you the how to for restricting users from accessing a VPN. Hopefully this will help with your restriction requirements. Alternatively, if you have already got your answer I would like to suggest updating your post and marking the solution for you and future users who may run across this same situation.