US Cable Support → Comcast HSI > [Connectivity] Why is my modem losing Internet connectivity?

[Connectivity] Why is my modem losing Internet connectivity?

Hello,

Background:

I live in an apartment complex which has an agreement with Comcast such that all residents are billed for basic cable service as part of the monthly rent. Supposedly, this enables residents to receive Comcast services at a better rate. Consequently, my Comcast account is classed as a Business Account, even though it is installed at my residence.

I elected to add additional services to my Comcast account:

Blast Internet
Extended HD TV

I really only care about the Internet. I don't have enough time in the day to watch TV, but its nice when relatives are in town visiting.

I have had these services for 6 months and they have worked flawlessly up until 2 weeks ago.

The problem:
Two weeks ago on a Sunday afternoon at about 3:30pm, I discovered that my smartphone was failing to access to the Internet (I had it configured to use my WiFi instead of LTE).

Investigating the problem, I discovered that my cable modem LEDs were not solid, indicating it was not linked to the Comcast network -- the download link LED would blink for a bit then become solid, then the uplink LED would blink for a bit and become solid, then the world-globe LED would blink for a bit and then the modem would repeat this sequence over and over.

My modem:
I purchased a brand new Motorol SURFboard eXtreme Wireless Cable Modem and Gigabit Router (SBG6580) when I began subscribing to Comcast 6 months ago. I purchased this modem because it is made by Motorola and supports the DOCSIS 3 standard, which is required to obtain the bandwidth speeds I pay for.

The first time this happened, 2 weeks ago, I called Comcast support to inquire about outages. They had me run through all the things I had already done (reset the modem, change coax and ethernet cables, etc.)

I should mention that while my Internet outage was present, my Comcast HD TV package continued work. I decided to temporarily move the modem to the jack the TV was using during this outage...and voila, the modem immediately linked up to the network as it normally would.

This behavior would suggest that the jack the modem is connected to is faulty -- except that is not the problem. Before going to bed, I again reconnected the modem to its original jack and reset it several times, each time not linking to Comcast. The next morning when I powered on the modem, everything worked (all I did was flip the same powerstrip button I had been using the night before -- no moving of cables, modem, etc.) This makes me think it is unlikely to be a short.

2 weeks went by and I noticed no problems -- everything working as expected.

Until last night around 10pm. I notice my laptop is not accessing a site. Again I check the modem and find the LEDs blinking in the same sequence as before. I cycle the modem power and it links up correctly...for about 5 minutes, then the LED flashing begins and is unresolvable for the remainder of the night and early morning.

We had heavy rain last night (not 2 weeks prior) so I called Comcast to inquire about outages in the area. I was advised there were none. All I did was power cycle my modem -- I didn't bother messing with the coax and ethernet. The wires are new and work just fine.

This morning I again turn the modem on and voila! Everything works again. Even right now I stopped by for lunch, turned the modem on and it works as expected.

So my question is, what is going on?! I don't believe the apartment wiring/jack is bad. If that were the case, the shorty wire would be easy to reproduce. I am suspecting that the cable guy somehow crossed the wire attached to my modem with another customer's jack...and perhaps when we both have our modems turned on, we both encounter Internet service disruption.

I do not know what the problem is and I don't want to spend anymore time troubleshooting it. I pay way too much for this stuff as is. I just want things to work. I haven't had a problem with Comcast until now and don't want to change, but I NEED my internet to work 24/7 and if I need to change to make that happen, I have no choice.

So I don't know what to do. I'm mainly posting this to inquire if my theory about my modem conflicting with another customers modem would produce this behavior?

I've been considering having the Comcast tech come out to look at my apartment jacks, but they tell me I will be billed if the issue is not with Comcast equipment...and its always working during the day (knock on wood), but I encounter these problems seeminly randomly after hours.

Anyways, looking for advice/suggestions before I switch back to fiber.

Thanks,
CR

You mentioned a short, it could be a break or lose connection that is so close that changes in temperature are making it open. Or it could be something adding noise to the cable that goes to that wall port.

Have you tried connecting it to the wall port for the TV any more times? If it always works on that port then you have a wiring/noise issue. If you don't want to have someone check the cables/connectors you could get a splitter and try running the modem and TV off that port.

You could plug a cable box into the port for the modem but that would only tell you if there was no signal, TV can still work with noise or low signal strength that would knock out the modem.

BTW: What are your signal levels when it is working well? I would also check the levels for the different wall ports and look for differences.

Re: [Connectivity] Why is my modem losing Internet connectivity?

the Amplifier (signal Booster) went bad. too much noise.