I have set up a site-to-site VPN to a company called Fortitude so that we can access another company's POS/Inventory solution.  It is all set up according to their specifications but it only works when they log in on their end and then shuts down after a while.  It's getting frustrating because the tech support will ping us and then tell us everything is fine but then after a while it quits working again.  I have tried to get them to help me with my settings to determine why the connection keeps dropping.  The only explination is I need to make sure the "keep alive" setting is enabled.  There is no "keep alive" setting, but there is a DPD setting that is enabled and set to 10 seconds which is the time that they want the "keep alive" setting on.  I'm getting frustrated and cannot understand why this is not working unless they initiate the connection.  Does anybody have any suggestions?