I have cable modem wired to the WAN side of my wireless router. Router gets its IP address, say x.y.z.q from the modem (DHCP).
If I am on the wireless LAN and I ping x.y.z.q does the reply come from the WAN side of the router, or from the modem itself?
Network interfaces are assigned IPs. Router would have (2) of same; modems do not provide DHCP. So, you're pinging WAN interface of router. Short latency is a clue, too.
Modems do not respond- they have no such "smarts"- they modulate/ demodulate, and have basic/limited additional functionality. Certainly not to include TCP/IP stack.
JYou are pinging the router. Look at the address your router shows for a defualt gateway and that should be the IP of your cable modem.
Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.