Just saw sessions showing in the NAT sessions table where the private IP was not in my subnet? Anyone else seen this?

did you make a note of the local and remote ports?

Unfortunatly not by the time I realised that might be a good idea they disappeared! I just dont understand how an IP outside my subnet can appear in the private IP list!

is vpn set up on that device?

generally you should only see your own subnet and public ips unless you have added some static routes or other private networks such as a vpn and that would be the only time you should see private networks outside of your subnet.

if you don't recognise the network then create a filter and block it!

I do have vpn enabled on the router but only for my own use when I am away from home. Makes me wonder if somone has managed to crack my password!

if its a dial in user vpn then the subnet of the dialin user would be on the same subnet of the router.

only lan to lan (site to site) vpn's require seperate subnets