accessing secure network with router

I just installed my mn700 wireless router. When I work
from home, I need to access a secure network via my web
browser. Now, after installing the router, my web browser
can't find the URL that I normally put in to access the
secure network. All other web browsing seems to work fine
though. When I use a dial up connection on another
computer at home, I can access the secure network without
any problem. Any ideas what the problem is??

Alan