If you get response as:
cat: /dev/net/tun: File descriptor in bad state --then TUN-TAP is enabled on your VPS successfully.
cat: /dev/net/tun: Permission denied -- then TUN-TAP is not currently enabled on your VPS. You need to contact our support department to get TUN-TAP enabled.
TUN-TAP has to be enabled by us only once, and will remain active inspite of OS reinstall.
Contact our support department for any further help.