Is it possible to connect to my Factory Reset Cisco 1841 router without the blue com cable? For instance is there a default IP address I can connect through one of the ethernet interfaces? I just did a "write erase" comman
You need to find a Cisco serial cable if you just did a
A factory reset requires a console connection because this erases the config on the router; you need console access to build the initial configuration.
As Mike already said: You have to do basic configuration using the cable. Most business-stuff has no default ip-address set. You typically see this only on SOHO equipment.
As for how to get a cable see my answer on question Is Selling Old Cisco Routers a Security Issue?
P.S. If you have HP ProCurve switches around the office: Their cables (the grey ones) are compatible as well.