Hi Boomer!
I apologize for not being here to help you.
Let me see.
On a wireless router/gateway, you should be able to access it from a computer that you have PLUGGED INTO IT by CABLE by typing the router address.
That should get you to a screen from which you can set up a wifi password of your own choosing.
BARRING THIS,
if you have at home an existing wireless router you are not using, or care to buy one cheaply ( I use TP LINK) you can connect a wireless router into an available port on the gateway supplied by comcast.
THEN, after plugging in your router you could connect one of your computers to the new wireless router by plugging a cable into the back of the new router and to the network adapter of your computer, be it a laptop or a desktop.
CHeck the paperwork that came with your new wi-fi router and see how to set up security settings and password. It will tell you what to type in your address bar and hit the enter key.
Then, once you have entered a password for your wi-fi setup, you should be able to connect to the new wireless router with every wireless computer you have.
This is a work around for ya that will work.
Hope this helps and I will check back!
My best to you Boomer!
micro.... 
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