Knowing the IP address of the default gateway (usually your router) on your home or business network is important information if you want to successfully troubleshoot a network problem or gain access to your router’s web-based management
In most cases, the default gateway IP address is the private IP address assigned to your router. This is the IP address that your router uses to communicate with your local home network.
While it might take a number of taps or clicks to get there, the default gateway IP address is stored in Windows’ network settings and is really easy to spot.
For Mac OS or Linux : Find default gateway IP address in Mac or Linux.