Cox provided instructions, that I don’t think make sense. My experience is that when you connect the new modem, you can’t access www.cox.com/activate. It may be possible to connect your modem, then activate via phone, but our cell overage is poor at our house so we have a cell extender, which doesn’t work when you install a new modem.

When I went to my new modem, I finally just called Cox tech support and gave them the MAC address and Serial Number by phone and they did the activation in real time. The time before that I actually stopped at the store and let them do it before I went home. 

I’d see if you can activate the new device while your old modem is connected, but I don’t know if that will work or not.

https://www.cox.com/residential/support/activating-a-new-modem-or-gateway.html

Thanks for the confirmation.  I’ll try it both ways and see what happens.

Your best bet is to take the new modem to a Cox store and ask them to set it up on your account. then when you get home it should be a matter of plugging it in and everything should work.

Thanks, I ended up working on the phone with cox after installing the modem and got everything going.  The install instructions could certainly be better