Get router IP on Mac OS

Using Terminal app

Go to the Launchpad.
Type “Terminal” in the search bar of the Launchpad.
Click on the “Terminal” icon.

When is open, type the following command:netstat -nr | grep default

This will output the following:
joe$ netstat -nr | grep default
default UGSc 50 46 en1

In this example is your default gateway (router) IP address.

Using Mac OS User Interface

In the top menu click "Apple" button.

Select "System preferences..." in the menu.

In the "System preferences" window select "Network"

Select your active Network connection in the list on the left. Usually you active connection will be already selected.

Click on Advanced... in the bottom right corner of the window.

Select TCP/IP from the Tabs.

You router IP address is in a Router line.