> I learned the problem connecting my new modem [...]
What, exactly, do you believe that your "the problem" is?
> [...] Comcast is only giving me 1 IP [address] [...]
That would be typical for residential service. Terminology:
https://en.wikipedia.org/wiki/Internet_Protocol
https://en.wikipedia.org/wiki/IP_address
> [...] but there are 4 ports on the modem which need? Separate IPs?
> [...]
A port on the modem doesn't need an IP address. A device which is
connected to one of those ports does need an IP address, which it would
get from your ISP. Up to the number of IP addresses which your service
agreement allows (typically one).
> [...] Suggestion on my other thread was to only use the first port.
That would be reasonable, if your service gives you only one IP
address.
> That may get me up but then I have 3 wasted ports I can't use and I
> need more output. [...]
If you didn't need those ports, then perhaps you didn't choose the
optimum modem model.
What, exactly, does "need more output" mean to you? What, exactly,
would you like to be able to do? Typically, a user who has multiple
devices will employ a NAT router to allow one external/public IP address
to serve multiple devices.
Incidentally, an Ethernet interface is bidirectional; there are no
input ports or output ports.
> [...] I'm connecting to the Netgear nighthawk mesh which only has 1
> Ethernet jack. [...]
Has your (unspecified) "the Netgear nighthawk mesh" a model number?
Look for "Model" on the product label.
> Can I configure the 4 modem ports to work off the same IP [address]?
No. As explained above, a modem port has no IP address. The device
which is connected to a modem port can have an IP address. Typically,
that would be the WAN/Internet port on a NAT router. Multiple devices
can't share that one external/public IP address. However, the use of
NAT allows multiple devices on your LAN (each with its own LAN IP
address) to appear to share that one external/public IP address, as seen
from the outside world.
