Using Smart VPN Client 4.3.1 running on Windows 8.1 I can successfully access my Draytek router. However, after a while the connection drops and any attempt to reconnect gives the error message "Can't find VPPP adapter !!!". After this the only fix is to reboot my laptop. Are there any know fixes to this problem?

I have a client who's also experiencing a similar problem on one particular machine, also Win8.1.
Doesn't appear to drop the connection, but will get the error message after waking from sleep.

Did you manage to resolve this, and if so how?