Need help changing IP address on new cox modem

When you changed the MAC address, whose MAC address did you use?  If you use a MAC address, that's assigned to a different device,  somewhere in the universe, you can cause all kinds of conflicts for yourself and your victim.   It's rare that someone actually legitimately NEEDS to force a new IP address.   Apparently, your new modem is using something different for a default gateway.  Something other than 192.168.1.1, which is probably the most common IP add for that as assigned by a "consumer" modem or router.  Get your computer to tell you what your default gateway is.

i changed my own mac address, anyway that is irrelevant i was just explaining how i changed my IP on my old modem. i do NEED to change my ip to avoid getting DDoSed. my new default gateway is 192.168.0.1, which is also the IP i type into my browser to access my new modem settings