PPTP VPN Disconnects after 10 minutes

[sororez]

Hi,

I have configured a PPTP VPN on my Fortigate - 300C Firmware v5.2.13 - with the below configuration:

config vpn pptp

    set status enable

    set eip 10.222.5.254

    set sip 10.222.5.1

    set usrgrp "VPN_PPTP"

end

The problem I am facing is that clients get disconnected exactly after 10 minutes. I wasn't able to find any timer settings for PPTP VPN. 

Anybody know what the issue might be.

Thanks