If using Windows, disconnects might occur every few minutes. These are caused by third party firewalls and anti virus software, which might be incompatible to the used PPTP VPN because they disconnect the needed control connection (TCP port 1723) after a short period of time.
To resolve this issue, you have to completely uninstall the third party firewall or the anti virus software. A deactivation is not sufficient. As firewall you can simply use the windows internal firewall. Compatible anti virus software are AVG Anti-Virus Free and AntiVir - Avira Free Antivirus. If this does not help, only a clean reinstallation of the operating system will get rid of all left over software.
As another option you can also use a wifi router. The router will connect to the login servers and provide Internet connection for all attached devices.
Thus you have the following options: