Lose remote connection to server through SBS Connection manager after two minutes...

Hello all, I have just moved most of my equipment form my home to a new office location and reconfigured my SBS2003 server and network to be accessed remotely via RWW thanks to the help of some of the great folks here on experts exchange. I have a question regarding remote access hardware VPN versus the SBS Connection Manager software VPN. Here is my config:

SBS2003 Server with two nics
SonicWall TZ170 on Server side with hardware VPN from
3COM OfficeConnect SecureRouter on Client side with a
Linksys Vonage VOIP Device (used for home phone line) attached to the OfficeConnect and a
3COM NBX VOIP Handset attached to the OfficeConnect Router

The OfficeConnect Router is necessitated by the need to deploy the 3COM NBX VOIP handset remotely. I have managed to get the handset to talk to the NBX Call processor which is on the "inside" server NIC (this is no mean feat).

I am putting the finishing touches on everything, and while RWW works perfectly, I am having an annoying problem with the connection manager dropping the vpn connection to the server after approximately two minutes. I am experiencing the exact same phenomenon on two different Vista workstations as well as an XP SP2 client (all at my home), which leads me to believe something is amiss on the server side and/or with the hardware VPN. Here is what is in the Connection Manager log:

******************************************************************
      Operating System      : Windows NT 6.0
      Dialer Version        : 7.2.6000.16386
      Connection Name       : Connect to Small Business Server
      All Users/Single User : Single User
      Start Date/Time       : 8/26/2007, 11:53:26
******************************************************************
      Module Name, Time, Log ID, Log Item Name, Other Info
      For Connection Type, 0=dial-up, 1=VPN, 2=VPN over dial-up
******************************************************************
[cmdial32]      11:53:26      03      Pre-Init Event      CallingProcess = C:\Windows\Explorer.EXE
[cmdial32]      11:53:26      04      Pre-Connect Event      ConnectionType = 1
[cmdial32]      11:53:26      06      Pre-Tunnel Event      UserName = NYEM50 Domain = NYECORP DUNSetting = Connect to Small Business Server Tunnel DeviceName = WAN Miniport (L2TP) TunnelAddress = xxx.no-ip.com
[cmdial32]      11:53:28      07      Connect Event      
[cmdial32]      11:53:28      08      Custom Action Dll      ActionType = Connect Actions Description = Configure proxy settings for IE. ActionPath = C:\Users\NYEM50\AppData\Roaming\Microsoft\Network\Connections\Cm\REMOTE\CMPROXY.DLL ReturnValue = 0x0
[cmdial32]      11:55:28      13      Disconnect Event      CallingProcess = C:\Windows\system32\CMMON32.EXE
[CMMON32]      11:55:28      26      External Disconnect due to Lost Connection      

It occurs to me that I can probably completely eliminate the SBS connection manager if I properly configure the hardware VPN between the SonicWall and OfficeConnect router... of course I don't know how to do that, and I'm afraid to mess with it too much for fear of knocing my handset offfline.