I m having a problem with my cisco 1841.
From the router i can ping external ip(22.214.171.124 or 126.96.36.199). but a user from vlan 11 can ping router wan interface 188.8.131.52 and default gw 172.25.11.1, but can't ping external ip.
Can you remove ip nat inside from Physical interface & configure the same one under all subinteface.
Can you post output of sh ver (IOS Ver.)