My VPN connection is disconnecting every 20 minutes, EventID 20226, code 631

Hi guys, I have a dedicated server hosted online running Windows Server 2008 Standard SP2, I installed my certificate on it and successfully managed to connect to my VPN (I use SONICWALL's Aventail Connect), this had been working like a charm for the past 4 month however since last week the VPN started to disconnect every 20 minutes or so, one thing I've noticed is that, before it would ask me to reconnect and now the connection just disappears without a sign, I would appreciate any help.

Thank you

btw: I did an extensive search on the forum before posting.

CoId={9CDA16BE-BBF5-4F74-B769-8139C97DD8EB}:
The user CUSTSERVER\SysUser dialed a connection named My VPN Connection which has terminated. The reason code returned on termination is 631.

- System

  - Provider

   [ Name]  RasClient

  - EventID 20226

   [ Qualifiers]  0

   Level 4

   Task 0

   Keywords 0x80000000000000

  - TimeCreated

   [ SystemTime]  2011-11-07T14:20:54.000Z

   EventRecordID 4937841

   Channel Application

   Computer CUSTSERVER

   Security


- EventData

   {9CDA16BE-BBF5-4F74-B769-8139C97DD8EB}
   CUSTSERVER\SysUser
   My VPN Connection
   631