On the vpn 3002 see if there are any messages related to DPD processing. Do the same on the remote vpn gateway that your 3002 connects to. Normally DPD is used to detect dropped connections and I'm thinking that one end is not receiving the dpd frames from the peer in a timely manner.
If possible, post here what type and what code the remote vpn gw is running. We may need to troubleshoot on that end.