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New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

cordcutters
Luminary

New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

New Netgear user here, hello! Need help please!

Just changed ISP's today (Spectrum to RCN) and with that needed to buy a better modem. Bought CM1200 (running Firmware Version V1.02.02) about 1 week ago and plugged in just today.

 

Using Macbook Pro laptop connected via Ethernet directly in one of the ports on back of CM1200.

 

My laptop is choosing a self-assigned IP beginning with 169.254 - which we know does not allow you to connect to Internet.

 

If I switch to Wifi on my laptop, I can connect to Internet just fine. The other 3 ports in the back of the CM1200 are Ethernet to: AppleTV, Roku, and of course Ethernet to router. Laptop connects to Wifi just fine. And the AppleTV and Roku work as well.

 

It's just that my laptop cannot access Internet via Ethernet - and continues to set its IP as 169.254.

I've spent almost 6 hours now, on the phone with Apple and my ISP and no one has an answer for a fix.

 

I understand some may reply with, well if the Wifi works why bother with Ethernet? I get that.

But I don't understand why this is only isolated to my laptop and no other devices Ethernet connected to the CM1200.

 

I have attached a screenshot of what the Network settings look like.

 

Does anyone have advice on how to fix this?

 

Thank you so much!

Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
Message 1 of 9
antinode
Guru

Re: New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

> Using Macbook Pro laptop connected via Ethernet directly in one of the
> ports on back of CM1200.

 

> [...] The other 3 ports in the back of the CM1200 are Ethernet to:
> [...]

 

   The CM1200 is a modem, not a modem+router.  How many devices were you
expecting to connect to it?  (Hint: For typical residential service,
more than one is probably the wrong answer.)

 

> [...] and of course Ethernet to router.

 

   Your (unspecified) "router" would be a good choice for that one
device to be connected to the CM1200.

 

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual.  Read.  Look for "LAN ports"
and "Connect Your Cable Modem to a Computer" (and the "Note" there).


   You have to admire the oblivion of the author/editor of a User Manual
for a cable modem which offers advice like:

 

      For more information, see the cable modem's user manual.

 

> I have attached a screenshot of what the Network settings look like.

 

   Most likely, your ISP will provide one external/public IP address to
your device(s).  If your router is working as expected, then I'd guess
that the router got it.  After that, I'd expect other devices to get
less cooperation from your ISP.

 

> Does anyone have advice on how to fix this?

 

   Connect (only) your router to your modem.  Connect your client
devices to your router.

Message 2 of 9
cordcutters
Luminary

Re: New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

Thank you @antinode for the explanation.

 

The product literature from the CM1200 Data Sheet as well as product description from the .com site list specs as: Number of Ethernet Ports: Four (4) Gigabit Ethernet ports with autosensing technology - and a Product Diagram which shows 4 of the same yellow color ports at the back of the device.

 

I've checked other sites and forums as well; a lot of folks are under the impresstion that the device has 4 equally usable ports, that directly connect the modem to up to 4 devices via ethernet cable, that all can be used at the same time. The fact that that is not true - misleads folks based on product descriptions, data sheets and product diagrams. Before my purchase I spoke with pre-sales dept and they assured me that all 4 ports directly connected to devices, used in tandem. I was pleasantly surprised (at that time).

 

I probably could have purchased the CM1000 because we only have 940gig Internet anyway (only bought that speed because of new customer promotion price for 14 mos.) so the CM1200 is not even necessary - and could've saved the $50.

 

Appreciate your reply though @antinode .

 

 

Message 3 of 9
antinode
Guru

Re: New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

> [...] a lot of folks are under the impresstion that [...]

 

   Yup.  A Web or forum search for your model number should find many of
them.

 

> [...] they assured me that [...]

 

   Trust no one, I always say.  It might be true, _if_ your Internet
service were unusual (multiple IP addresses).  But, even so, connecting
a typical computer directly to the Internet that way (without a NAT
router in-between, acting as a firewall of sorts) would be a serious
security risk.

 

   If I wrote Netgear's documentation, many things would be different.

Message 4 of 9
FURRYe38
Guru

Re: New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

Just because it has 4 ports on the back of the CM1200 doesn't mean it has a router or you can connect anything to these ports. Further informnation about this modem says that these ports are for ISP WAN IP addressing on ports 2-4. These are WAN side ports only. So you have a ISP and a business need for having 4 different WAN IP addresses from your ISP, this modem fits that need. 

 

Please don't assume that if a modem has 4 ports that there would be a router. You can assume that for the C series modems, yes this is the case for those series modems as they do have built in router. For the CM series, these modems do not have a built in router. Yes, you may see more than one WAN port on these modems, CM1100 and CM1200 are the only models that have these additional WAN ports for only WAN side ISP assigned IP addresses from them. 


@cordcutters wrote:

 

 


 

My Setup ISP SparkLight | Internet Cable 1000↓/50↑ CM1200 Modem |  Wifi Router Orbi RBK853 (Router Mode), Wired Backhaul and RBK752 | Switches NG GS105/8, GS308v3, GS110MX and XS505M | 

Additional NG HW: C7800/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: R7000, R7800, R7960P, R8000, R8500, RAXE500, RAX50, XR450, EX7500/EX7700

Message 5 of 9
SPdevotee
Luminary

Re: New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

Similar problem I think I ran into.  I think the solution is to not connect additional devices to the CM1200.

 

My Netgear AX1800 only has 1 LAN port so do I then need an AP after it to allow mutliple wired connections from the router?

Message 6 of 9
SPdevotee
Luminary

Re: New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

What is a NAT router?

Message 7 of 9
antinode
Guru

Re: New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

> [...] I think the solution is to not connect additional devices to
> the CM1200.

 

   One might get that impression from reading this thread.

 

>    Connect (only) your router to your modem. [...]

 

   Which part of that was unclear?

 

> My Netgear AX1800 only has 1 LAN port [...]

 

   What is it?  "AX1800" is a speed, not a model number.  Look for
"Model" on the product label.

 

> [...] do I then need an AP after it to allow mutliple wired
> connections from the router?

 

   "the router"?  Have you a router?  Has it a maker and a model number?
Care to share?


   An "AP" normally means an "access point", which is an abbreviation of
a "wireless access point".  Not normally required to add "wired
connections from" anything, but typically could be used that way.

 


> What is a NAT router?

 

   A router which does NAT.  (Is Google broken?)

 

      https://en.wikipedia.org/wiki/Network_address_translation

 

   Practically any router which you'd be likely to buy would do NAT.

 


   You might want to start your own, new thread, for your own, different
problem(s).  Include an accurate, useful description of your devices,
and of what's connected to what.  (Hint: If a device has different types
of Ethernet ports, then "connected to device" is not enough detail.)


   What you're actually trying to do might be interesting, too.

Message 8 of 9
FURRYe38
Guru

Re: New CM1200 - self-assigned IP address via Ethernet Connected Laptop - NO Internet

Pg 3 gives a diagram of how how to connect a router to the CM modem or just 1 wired PC:

https://www.netgear.com/images/datasheet/networking/CableModems/CM1200.pdf


@SPdevotee wrote:

What is a NAT router?


 

My Setup ISP SparkLight | Internet Cable 1000↓/50↑ CM1200 Modem |  Wifi Router Orbi RBK853 (Router Mode), Wired Backhaul and RBK752 | Switches NG GS105/8, GS308v3, GS110MX and XS505M | 

Additional NG HW: C7800/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: R7000, R7800, R7960P, R8000, R8500, RAXE500, RAX50, XR450, EX7500/EX7700

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