We have a Cisco 3700 router that has been working for years using the default route 'route ip 0.0.0.0 0.0.0.0 F0/0'. Strangely, our connection(in/out) suddenly dropped and the only solution that worked was to set the default route to 'route ip 0.0.0.0 0.0.0.0 22.214.171.124'.
ISP's provided gateway 126.96.36.199
F0/0 - 188.8.131.52
F0/1 - 184.108.40.206
Any idea what happened?