Ethernet connection issues CM1150V

If you only have 1 router then you can only use either port#1 if the external router doesn't support LAG. 
If the external router supports LAG then you can enable LAG on both CM modem and external router then connect the router to Port 1 and 2 only. 

LAG routers I know of are NG Orbi AX, R7960P/8000P, There RAX series may also support LAG. Some ASUS routers like there GT-AX1100 does and presume other ASUS model routers. 

Now if you had two external routers, no LAG, you can connect 1st router to Port #1 and the 2nd router to Port #2. If you had 3 routers, then you would connect the 3rd router to Port #3. I presume if you had a 4th router, it would connect to Port #4.

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daviburg wrote:

I have the CM1150V modem and would be much interested in learning the exact steps to get ports 1 and 3 working simultaneously for one router each while having a single gigabit service with the ISP. Please include which ISP it worked with when posting details as the ISP controls the firmware version and update on the modem. Also include which router(s) make and model worked.

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The modem was orignally configured with a Checkpoint router in Port 1.  Assuming the ports were paired (1-2, 3-4) for purposes of link aggregation, I chose to connect the secod router (a much older fast ethernet Checkpoint) to Port 3.  Before powering up the router I wired it to modem Port 3 and hardwired a MSFT Surface to LAN Port 1; and then I plugged it in.  The router LEDs indicated functioning WAN and LAN connections.  On the surface I pinged the router and in a command window ran ipconfig /all |more to find that the Surface appeared to be connected to the ISP.  I then just loaded a browser, navigated to google and looked up somethig new to make sure i wasn't just loading previously cached data, and then ran speedtest for good measure.  At the same time the principal network continuted to function normally. 

My reasons for not being surprised (but I wouldn't have been surprised if it had turned out not to work) include the following (mostly logical surmise, without benefit of the technical detail that is above my paygrade). 

1.  When you use a separate modem and router, the ISP's interaction is with the modem, not the router.  I'm no technician, but I'm not even sure the ISP knows or cares what router is behind the modem, asl long as it is compatible with the modem (which the modem figures out for itself).    At another location I had a separate modem/router setup, and when the router became too dated I swapped it out for an up- to date router, and I am pretty sure that doing so inovolved no intereaction with much less intervention by or permission from the ISP.  The ISP assigns an IP address to the modem, not the router, unless the you're using (as I suspect most users are) a combination cable modem/router. 

2.  When you connect a router that provides both wired and wireless LAN connections (and I don't recall every having seen a wireless-only router), you are, in effect, running two separate networks -- wired and wireless -- from the router.   If so there is nothing intrinsically different about running separate networks by hanging separte routers off the modem, at least if it has the ethernet ports (as most modems do not) sufficient to accomodqte more than just one.  The CM1100 apparently has two; the CM1150V has four.  I've satisfied myself that this works off Ports 1 and 3 of a CM1150V, and I'm glad I followed your advice to buy it and try it. 

3. Not that I trusted it, but I did contact tech support at the ISP in advance of buying the modem and upgrading my service to ask whether a modem could support more than a single router.  From the questions he asked I'm not sure the tech had ever encountered a modem with more than one ethernet port, but once he understood that I was talking about a modem with multiple ports, his answer was "sure?", which I interpreted as "at least I think so."  As I said, I didn't take that to the bank, and one of the techs who did the instillation said "No way" (though I think she was not having her best day).  But as it happens the guy in tech support appear to have been right. 

4.  Finally, to whomever it was that kept saying this is a "theft of internet services," my short answer is "I don't think so."  The ISP interacts with the modem, and controls the rate at which date is transferred to and from it and you by the way it provisions service to the modem.  If, as in our case, that speed is set at 300Mbs, that's the the top rate at which it will permit water to come through the hose.  If on the other side of the modem you choose to divide that between wired and wireless LANs, or between two seprate routers, I don't quite see how each of them can spout water at 300 if no more than 300 is permitted into the connection wih the modem to begin with.  It's just a matter of how you want to allocate the bandwith that you have chosen to buy from the ISP. 

So, that's what I have learned.  Thanks again, Furrye38, for the advice.