The setup ...

2925 with fixed public IP.
2925 LAN 1 192.168.1.x, DHCP disabled, VLAN 0
2925 LAN 2 192.168.123.x, DHCP enabled, VLAN 123
LAN-to-LAN SSL VPN dial-in profile set up on port 4434, also set in General Setup

2860 using 4G dongle and therefore no fixed public IP.
2860 LAN1 internal IP range 192.168.10.x, DHCP enabled, VLAN 0
2860 has a VOIP phone on LAN 4 with internal IP range 192.168.4.x, DHCP enabled, VLAN 10
LAN-to-LAN SSL VPN Dial-Out profile set up on port 4434.

When the 2860 connects I see the tunnel come up on the connection manager of the 2925 for about a minute but no traffic, then the 2860 reboots. This will keep cycling like this every minute until I disable the VPN profile on the 2925.

If I set up a VPN on another remote 2925 that's got a standard broadband WAN then it all works without any problems.

How can I troubleshoot this. I'm pretty sure the 2860 shouldn't be causing the problem whereby it reboots itself!

Thanks.