Intermitten Internet Disconnection

Start here;

https://forums.xfinity.com/t5/Your-Home-Network/Internet-Troubleshooting-Tips/m-p/3310447#M316652

I checked through all of these and found that I am receiving multiple T3 and T4 timeouts a day. Inspected the cables outside and noticed that they led to an old box that didnt even have a cover attached to it. Does Xfinity maintain these lines?

They're *supposed* to.

What do the modem's signal stats look like ? Try getting them here http://192.168.100.1 or here http://10.0.0.1

Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.

What is the exact make and model number of the modem ?

If the images didnt work here is a list of the values.

Downstream Power/SNR:

1 = -1.2/39.9

2= -1.2/39.8

3= -1.1/39.8

4= -0.8/39.2

5=  -0.7/39.8

6= -0.5/39.9

7= -0.4/40

8= -0.3/40

9= -0.1/40.1

10= -0.2/39.8

11= -0.2/40.1

12= -0.3/40.1

13= -0.2/40.2

14= -0.4/40.1

15=  -0.5/40.1

16= -0.5/40.1

Upstream Power:

1= 44

2= 43.1

3= 44

4= 44.9

All the power levels seem to be in the correct range.

Modem:

CM500-100NAS 

Firmware Version V1.01.12

Downstream:

Downstream:

Upstream:

Those are good. What about the SNR's ?

My bad. I overlooked them. Sorry. All the stats are fine. You didn't post the make and model number of the modem ? And please also post the error log entries.

NETGEAR 

CM500-100NAS 

Firmware Version V1.01.12

there is a MAC and Serial number but I dont imagine you would need either

Please look at top of post, these are all already posted. @EG 

What are other causes of T3 and T4 disconnects? Also there seems to be something really strange going on with the clock resetting to 1970.

The signal stats are o/k but the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) somewhere.

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !

---

@drewbotts wrote:

What are other causes of T3 and T4 disconnects? Also there seems to be something really strange going on with the clock resetting to 1970.

---

That's what happens when a line signal impairment (typically noise ingress) prevents the modem from being able to hear / talk to the T.O.D. (Time Of Day) server, it defaults to using that time / date stamp.

3-Critical R2.0 No Ranging Response received - T3 timeout:

Explanation. The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also lower the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem's power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process.
Recommended Action No action is needed if this is an occasional problem. Check the upstream transmit power for the cable modem to see if it is at or near the maximum allowable levels. Check the RF plant for cabling or connector issues that could generate sufficient noise to lose MAC-layer management messages.

3-Critical H501.8 HFC: T4 Timer Expired:

Explanation. The cable modem did not receive a station maintenance opportunity in which to transmit a Ranging Request (RNG-REQ) message within the T4 timeout period (30 to 35 seconds). The cable modem is resetting its cable interface and restarting the registration process. Typically, this indicates an occasional, temporary loss of service, but if the problem persists, check for possible service outages or maintenance activity on this particular headend system.
Recommended Action for your Provider: Check the configuration on the CMTS. Check the cable plant for RF connector or cabling issues that could be generating noise on the downstream and upstream.

Thanks @EG! You've been a lot of help