No Ranging Response Received - T3 time-out

[me456]

Hello, I have been getting intermittent connection issues for past few months, the connection would drop and back online in few minutes or up to an hour in some cases. This consistenly happens at least once in the evening. I use Surfboard Model SB6120 and the modem log shows "No Ranging Response Received - T3 time-out", at the time when the issue happens. 

I see other threads that there is some issue with the uplink and requires tech visit. Can you advice how this could could be fixed?

[CCAndrew]

You might start with a modem that Comcast still supports.
https://www.xfinity.com/support/devices/#auth

[me456]

Thank you. I will upgrade the modem and try.

[EG]

What do the modem's signal stats look like ? 

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

[me456]

Hello, I upgraded my modem to Motorola MB8600 and still getting timeouts almost every day. But now the timing varies. Below is signal status from the modem log.

Channel	Lock Status	Modulation	Channel ID	Freq. (MHz)	Pwr (dBmV)	SNR (dB)	Corrected	Uncorrected
   1	Locked	QAM256	4	405.0	1.1	42.9	2353085	961134
   2	Locked	QAM256	5	411.0	0.7	43.2	2285858	881262
   3	Locked	QAM256	6	417.0	0.9	43.1	2208827	835464
   4	Locked	QAM256	7	423.0	1.1	43.4	2205695	903677
   5	Locked	QAM256	8	429.0	1.3	43.5	2171252	814664
   6	Locked	QAM256	9	435.0	1.1	43.3	2094493	828292
   7	Locked	QAM256	10	441.0	1.1	43.2	2008460	821520
   8	Locked	QAM256	11	447.0	1.4	43.2	1933202	700520
   9	Locked	QAM256	12	453.0	1.3	42.8	1959323	766156
   10	Locked	QAM256	13	459.0	1.6	42.7	1829146	593643
   11	Locked	QAM256	14	465.0	2.1	43.0	1828913	609667
   12	Locked	QAM256	15	471.0	1.8	42.9	1698564	521560
   13	Locked	QAM256	16	477.0	1.7	42.8	1650302	492846
   14	Locked	QAM256	17	483.0	1.9	42.8	1591790	462674
   15	Locked	QAM256	18	489.0	1.6	42.8	1584522	464177
   16	Locked	QAM256	19	495.0	1.3	42.4	1726248	650420
   17	Locked	QAM256	20	507.0	1.9	42.9	1412136	338393
   18	Locked	QAM256	21	513.0	1.5	42.4	1367609	312772
   19	Locked	QAM256	22	519.0	1.7	42.8	1271078	261682
   20	Locked	QAM256	23	525.0	2.1	42.7	1263550	269871
   21	Locked	QAM256	24	531.0	2.0	42.6	1266313	288323
   22	Locked	QAM256	25	537.0	1.6	42.5	1204633	250724
   23	Locked	QAM256	26	543.0	2.0	42.8	1137397	234544
   24	Locked	QAM256	27	549.0	2.1	42.6	1119143	248499
   25	Locked	QAM256	28	555.0	1.7	42.3	1136642	229738
   26	Locked	QAM256	29	561.0	1.7	42.2	1145538	241779
   27	Locked	QAM256	30	567.0	2.0	42.3	961066	167072
   28	Locked	QAM256	31	573.0	1.7	42.2	1072411	254417
   29	Locked	QAM256	32	579.0	1.3	41.6	1068674	208590
   30	Locked	QAM256	33	585.0	2.5	42.0	915878	154361
   31	Locked	QAM256	34	591.0	2.9	41.7	860636	152022
   32	Locked	OFDM PLC	48	688.0	2.5	37.0	89011829	64391


   Upstream Bonded Channels		 	
  
   Channel	Lock Status	Channel Type	Channel ID	Symb. Rate (Ksym/sec)	Freq. (MHz)	Pwr (dBmV)
   1	Locked	SC-QAM	1	5120	17.3	53.5
   2	Locked	SC-QAM	2	5120	23.7	53.5
   3	Locked	SC-QAM	3	5120	30.3	53.5
   4	Locked	SC-QAM	4	5120	36.7	54.3

[EG]

The upstream power is too high and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

[me456]

Thanks for the suggestion. I have only one splitter which is between the cable box and home. Splitter seems to be good quality and has been using for past few years and for testing, I connected the modem directly to the main cable bypassing the splitter and noticed upstream power has reduced. Is this power level in acceptable range?  Below the upstream signal status with and wthout splitter. Unfortunately bypassing the splitter is not an option, would adding an amplifier or signal booster help?

Signal status without splitter 

-------------------------------------------

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
1 Locked SC-QAM 1 5120 17.3 46.0
2 Locked SC-QAM 2 5120 23.7 46.0
3 Locked SC-QAM 3 5120 30.3 46.5
4 Locked SC-QAM 4 5120 36.7 46.0

My original endpoint with splitter and additional cable length of 10 meteres

-----------------------------------------------------------------------------------------------------------

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
1 Locked SC-QAM 1 5120 17.3 51.3
2 Locked SC-QAM 2 5120 23.7 51.3
3 Locked SC-QAM 3 5120 30.3 51.3
4 Locked SC-QAM 4 5120 36.7 51.3