TechSpot published A list of common default router IP addresses
A quote from the article:
Here's the scenario: you are helping a relative with network issues and need to access their router's browser interface. You can typically find the information by entering 'ipconfig' into the Windows command prompt, but if for some reason you can't retrieve the router's IP address using that method, we've compiled a brief list of popular router brands and their common default addresses. The list includes most router manufacturers with more than a dozen or so models.A list of common default router IP addresses @ TechSpot