I've set VPN Access in manual and granted an access for a subnet. But the unselected subnet(Not granted) is still accessible using VPN Connection. Is this known issue in Softlayer ? I tried this in "control.softlayer.com"
Probably, you are doing the changes after you have logged in VPN Access, that's the reason why the restrictions were not taking effect.
You should logging again after you have been done the changes, in order that they can take effect.