Community Forum

unstable internet connection

Highlighted
Regular Visitor

unstable internet connection

Hi - I have a 500 Mpbs plan and generally get good speeds but face unstable internet throughout the day with drops and vast reductions in speeds for a couple minutes at a time.  I have a Netgear CM1150V.  Here is the report on the connection from the modem below.  Any advice?

 

Frequency start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency
 
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 603000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 32 603000000 Hz -5.2 dBmV 38.4 dB 5050134 1495290
2 Locked QAM256 17 513000000 Hz -2.9 dBmV 39.9 dB 364 296
3 Locked QAM256 18 519000000 Hz -3.1 dBmV 39.9 dB 385 278
4 Locked QAM256 19 525000000 Hz -3 dBmV 39.9 dB 290 72
5 Locked QAM256 20 531000000 Hz -3.2 dBmV 39.8 dB 291 39
6 Locked QAM256 21 537000000 Hz -2.9 dBmV 39.8 dB 397 91
7 Locked QAM256 22 543000000 Hz -3 dBmV 39.7 dB 545 162
8 Locked QAM256 23 549000000 Hz -3.2 dBmV 39.7 dB 472 187
9 Locked QAM256 24 555000000 Hz -2.9 dBmV 39.6 dB 475 212
10 Locked QAM256 25 561000000 Hz -3.1 dBmV 39.5 dB 439 48
11 Locked QAM256 26 567000000 Hz -3 dBmV 39.5 dB 485 42
12 Locked QAM256 27 573000000 Hz -3 dBmV 39.5 dB 636 38
13 Locked QAM256 28 579000000 Hz -3.4 dBmV 39.3 dB 663 39
14 Locked QAM256 29 585000000 Hz -3.6 dBmV 39.2 dB 725 37
15 Locked QAM256 30 591000000 Hz -4.3 dBmV 39 dB 649 37
16 Locked QAM256 31 597000000 Hz -5 dBmV 38.8 dB 651 44
17 Locked QAM256 33 609000000 Hz -5.3 dBmV 38.4 dB 968 46
18 Locked QAM256 34 615000000 Hz -4.4 dBmV 38.8 dB 972 39
19 Locked QAM256 35 621000000 Hz -3.9 dBmV 38.9 dB 844 33
20 Locked QAM256 36 627000000 Hz -3.6 dBmV 38.9 dB 847 37
21 Locked QAM256 37 633000000 Hz -3 dBmV 39 dB 850 42
22 Locked QAM256 38 639000000 Hz -3.1 dBmV 39 dB 757 37
23 Locked QAM256 39 645000000 Hz -2.8 dBmV 39 dB 570 41
24 Locked QAM256 40 651000000 Hz -3.4 dBmV 38.8 dB 767 42
25 Locked QAM256 41 657000000 Hz -3.9 dBmV 38.7 dB 694 42
26 Locked QAM256 42 663000000 Hz -3.6 dBmV 38.7 dB 878 43
27 Locked QAM256 43 669000000 Hz -4 dBmV 38.5 dB 959 119
28 Locked QAM256 44 675000000 Hz -3.8 dBmV 38.2 dB 1056 163
29 Locked QAM256 45 681000000 Hz -3.8 dBmV 38.5 dB 908 156
30 Locked QAM256 46 687000000 Hz -4.1 dBmV 38.4 dB 970 115
31 Locked QAM256 47 693000000 Hz -3.6 dBmV 38.6 dB 830 124
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 1 5120 Ksym/sec 19300000 Hz 48.3 dBmV
2 Locked ATDMA 2 5120 Ksym/sec 25700000 Hz 48.5 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 32300000 Hz 48.5 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 38700000 Hz 48.5 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
 
Downstream OFDM Channels
Channel Lock
Status
Modulation /
Profile ID
Channel
ID
Frequency Power SNR /
MER
Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1 Locked 0 ,1 ,2 ,3 48 850000000 Hz -7.4 dBmV 35.8 dB 1348 ~ 2747 4740107085 4266588082 18561
2 Not Locked 0 0 0 Hz 0 dBmV 0.0 dB 0 ~ 4095 0 0 0
 
Upstream OFDMA Channels
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Not Locked 0 0 0 Hz 0 dBmV
2 Not Locked 0 0 0 Hz 0 dBmV
Highlighted
Expert

Re: unstable internet connection

The upstream power is on the high side and it may be intermittently fluctuating even higher to out of spec levels. The downstream power is a bit on the weak side as well. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, and latency problems.

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.



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Regular Visitor

Re: unstable internet connection

removed the splitter and directly connected the line to the modem.  These are my numbers below.  will this be more stable?  The splitter was installed a couple years ago by XFinity.  Not a cheap radioshack model.

 

Frequency start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency
 
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 603000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 32 603000000 Hz 4.3 dBmV 39.3 dB 5050417 1495647
2 Locked QAM256 12 477000000 Hz 3.6 dBmV 39.7 dB 404 406
3 Locked QAM256 13 483000000 Hz 4.2 dBmV 40 dB 542 846
4 Locked QAM256 14 489000000 Hz 4.6 dBmV 40 dB 11917 11665
5 Locked QAM256 15 495000000 Hz 4.9 dBmV 40 dB 9412 12256
6 Locked QAM256 16 507000000 Hz 4.9 dBmV 40 dB 1167 2588
7 Locked QAM256 17 513000000 Hz 4.6 dBmV 39.8 dB 2615 6500
8 Locked QAM256 18 519000000 Hz 4.5 dBmV 39.9 dB 2770 8288
9 Locked QAM256 19 525000000 Hz 4.5 dBmV 39.8 dB 7905 25040
10 Locked QAM256 20 531000000 Hz 4.2 dBmV 39.7 dB 5557 21019
11 Locked QAM256 21 537000000 Hz 4.5 dBmV 39.7 dB 4644 6199
12 Locked QAM256 22 543000000 Hz 4.3 dBmV 39.7 dB 3450 5629
13 Locked QAM256 23 549000000 Hz 4.3 dBmV 39.7 dB 3031 5706
14 Locked QAM256 24 555000000 Hz 4.6 dBmV 39.7 dB 3145 5878
15 Locked QAM256 25 561000000 Hz 4.5 dBmV 39.6 dB 3404 6662
16 Locked QAM256 26 567000000 Hz 4.7 dBmV 39.6 dB 2979 7325
17 Locked QAM256 27 573000000 Hz 4.7 dBmV 39.6 dB 3621 7428
18 Locked QAM256 28 579000000 Hz 4.5 dBmV 39.4 dB 3330 7097
19 Locked QAM256 29 585000000 Hz 4.5 dBmV 39.4 dB 3183 7280
20 Locked QAM256 30 591000000 Hz 4.2 dBmV 39.4 dB 3222 7006
21 Locked QAM256 31 597000000 Hz 4.2 dBmV 39.4 dB 3134 7088
22 Locked QAM256 33 609000000 Hz 3.9 dBmV 39 dB 2782 6738
23 Locked QAM256 34 615000000 Hz 4.2 dBmV 39.1 dB 2959 7377
24 Locked QAM256 35 621000000 Hz 4.3 dBmV 39.1 dB 3096 7530
25 Locked QAM256 36 627000000 Hz 4.5 dBmV 39.1 dB 4925 7826
26 Locked QAM256 37 633000000 Hz 5 dBmV 39.2 dB 3222 7683
27 Locked QAM256 38 639000000 Hz 4.9 dBmV 39.2 dB 3282 7495
28 Locked QAM256 39 645000000 Hz 5.2 dBmV 39.2 dB 3358 7055
29 Locked QAM256 40 651000000 Hz 4.7 dBmV 39 dB 3175 6993
30 Locked QAM256 41 657000000 Hz 3.9 dBmV 38.8 dB 3200 6985
31 Locked QAM256 42 663000000 Hz 3.7 dBmV 38.7 dB 3224 7115
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 1 5120 Ksym/sec 19300000 Hz 42.3 dBmV
2 Locked ATDMA 2 5120 Ksym/sec 25700000 Hz 42.3 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 32300000 Hz 42 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 38700000 Hz 42.3 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
 
Downstream OFDM Channels
Channel Lock
Status
Modulation /
Profile ID
Channel
ID
Frequency Power SNR /
MER
Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1 Locked 0 ,1 ,2 ,3 48 850000000 Hz -0.2 dBmV 35.9 dB 1348 ~ 2747 4908759237 4418042191 18561
2 Not Locked 0 0 0 Hz 0 dBmV 0.0 dB 0 ~ 4095 0 0 0
 
Upstream OFDMA Channels
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Not Locked 0 0 0 Hz 0 dBmV
2 Not Locked 0 0 0 Hz 0 dBmV