milliki77 If you are paying a rental fee for the Panoramic, you should seriously consider purchasing your own DOCSIS 3.1 cable modem and using your old router instead. In the long run, you'll save money -and- get more features.
That being said... You can certainly use your old router in what is called "bridge" mode or sometimes "repeater" mode. You'll need to consult the manual as different routers support different set ups and features when in these modes. For example, the "guest wifi" feature of your old router may not be available when the router is configured in "bridge" mode.
I suspect the Cox "guest wifi" feature was removed in favor of the "Cox Wifi Hotspot" feature (which doesn't help your guests as you noted)... or perhaps the cheaply made (but expensive to purchase) mesh points don't support multiple wifi networks.
