I've been using a Cisco 881W router with a Cisco-supplied config to make an Easy VPN connection to the sandbox (a Collaboration 10.5 lab in rave08). Everything has been working fine for the last two days, until a couple of hours ago when I lost access to the sandbox network (e.g. CUCM on 10.10.20.1 fails to respond to ping and HTTP, Windows DNS Server on 10.10.20.100 fail to respond to ping and DNS). I can access CUCM via https://devnetsandboxlabs.cisco.com/rave08, so the instance itself seems healthy.
As far as I can tell there have been no local changes which would have affected this, and the lab has 1d18h left to run. The 881W's VPN light is illuminated and tracert 10.10.20.1 gets as far as 192.168.200.254 before timing out.
I'm wondering whether the VPN group, key etc. are wrong, but the fact that it has worked for two days would suggest not. Is there a definitive reference for what these should be for a given lab / rave? Are there any current issues which might explain what I'm seeing?