FG310B - L2TP configuration using Microsoft Client L2TP over IPSec multiple clients

Hello,

I am replacing an old L2TP Server and want to use the Fortinet.  I need to use the Windows standard client so that I don't need any client changes because I'm in a bit of a rush.  I've been able to make this work just fine for most of the clients.  The one area that is not working is if two clients are behind the same firewall and each tries to establish a L2TP/IPsec connection to the Fortinet.  The connections seem to step on each other.

Is there something I am missing to enable this?  Or is this a natural shortcoming.  I was able to do this with my old L2TP Server.

We are currently running 5.2.10.

Thanks.

Chuck.