To run this process on your Apple Mac, you will need to know your Mac's Admin Password.

Open a Finder window.

Select Applications from the sidebar

Double click Utilities

Double click Terminal

In the terminal window, type:

sudo nano /etc/hosts and then hit enter

Enter the admin password for your Mac and hit enter

This will open the NANO editor.  You should see something similar to below.  

Navigate to the bottom of the file using the arrow keys and position it on a new line.

Type the following (use the TAB key in between the IP Address ( and the beginning of the rdgw... address.

Once you're done, hold down the control and O keys to save the file, then control and X to exit.

You could double check the entry has been added to the file by opening the file again using the sudo nano /etc/hosts command.

Close the Terminal Window

Reboot your Mac.