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Xfinity cable modem/wifi router combined

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Frequent Visitor

Xfinity cable modem/wifi router combined

Can anyone at Comcast Support answer a question for me? I have a recently-acquired (last week) Comcast cable modem with WiFi built in. An enormous, heavy modem, compared to past modems! When I plug in my 8-port ethernet switch, the modem transmits a clean relatively fast internet signal to all 8 ports. The small LED beside the modem ethernet port is green. When I plug in my 4-port ethernet switch to one of the modem ports, the small LED on the other side of the port is red. Thinking the switch was bad, I tried another 4-port switch of another brand, and it displayed the red LED. Then I tried a 3rd switch, and it displayed the red LED. Do I think all 3 switches are bad? Heck No! Also, interestingly I can get a clean internet signal (using a laptop to test) out of all 3 switches in spite of the red LED.

Can anyone tell me what that red LED is trying to tell me? There were no instructions with this modem except the self-install, which didn’t work anyway, requiring assistance from a telephone support person. If there is a link to detailed instructions regarding this modem, with details of the output from each of the ethernet ports on it, send me that.

By the way, I’m still not certain that Comcast has not disabled my personal modem (Arris SB8200, recommended by Comcast!). They have done it twice before, claiming I hadn’t given them the MAC ID. I had, THREE times!

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Diamond Problem Solver

Re: Xfinity cable modem/wifi router combined

Did you happen to read the instructions of any of the 3 switches to see what the lights mean? Lights are generally an indication of speeds the switch port is utilizing, without any model provided it would be hard to tell definitively

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Frequent Visitor

Re: Xfinity cable modem/wifi router combined

Sorry! Not sure what you mean. Lights on ethernet switches always blink green since I have been using them for about 10 years. (I believe switches are either Dynex or Netgear.) The red or green light I am referring to appears under and to the left or right of the ethernet plug which is plugged into this massive cable modem. Still looking for some detailed instructions or a diagram as to what the various ports represent and/or LED lights under the ports. There appears to one port specifically for a VOIP telephone, which I don't have and won't try to use otherwise unless so instructed.

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Frequent Visitor

Re: Xfinity cable modem/wifi router combined

They are labelled 10/100 switches, about 10 years old. So is the 8-port switch which seems to play "nice" with the massive Xfinity cable modem! In other words, the latter has a green LED beside the modem port when plugged into it.

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Expert

Re: Xfinity cable modem/wifi router combined


@bjkline wrote:

They are labelled 10/100 switches, about 10 years old. So is the 8-port switch which seems to play "nice" with the massive Xfinity cable modem! In other words, the latter has a green LED beside the modem port when plugged into it.


It's possible, since those switches are so old, that you're going to need a crossover ethernet cable to use them.They're not used so much anymore since most routers and switches have MDX-I (Autoconfiguration) enabled.

See: https://www.lifewire.com/crossover-cable-ethernet-817870

 

Personally, I'd just junk those ancient 10/100 switches and use a newer one to take advantage of your gateway's throughput.


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Frequent Visitor

Re: Xfinity cable modem/wifi router combined

Have ordered replacement of all ethernet switches in house with 1-2G switches, just as an experiment to see if I do see an increase in speed with any of devices. Whenever I run a speed test on several of my PC's, I see close to what Comcast claims I am paying for (except when they throttle it back due to demand!). Also will be interesting to see if Comcast cable modem displays any different LED's at ethernet ports with new devices. Thanks for the suggestion. Will let you know results, but will probably be several weeks away.

Just for the record, my (5-yr.?) old Wi-Fi router puts out a much faster/stronger signal than that emanating from the Comcast combined modem/router.

Still would love to see details of the various ports and lights on Comcast cable modem.