I managed to access the router status and it shows ssid as smarter broadband (my broadband provider is Chess) not sure but could the same ip address be assigned to two different isp ?
No but Chess seem to use the "Smarter" branding on parts of their website, it's possible that smarter is just resold Chess.
Is your external IP address set on the router or do you use DHCP on the WAN side? If it is set in the router then it is possible your ISP "forgot" you were on a fixed IP and gave it to someone else. If it's on DHCP it shouldn't matter, you would just get a different one allocated. If you have the IP address set then try DHCP instead.
Then again that doesn't explain how you were able to access your router from outside up until rebooting it.
Edited by Backpack (Sun 06-Jan-13 04:38:31)