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Frequent 20Mbps download speed on a 600Mbps plan with SB8200 ARRIS Cable Modem

linded
Regular Visitor

Frequent 20Mbps download speed on a 600Mbps plan with SB8200 ARRIS Cable Modem

 

Upgraded to 600 Mbps plan in 2019, purchased an ARRIS SB8200 Cable Modem, and registered it with Comcast.  Comcast had to do something(don't recall) before I saw 300 to 400 Mbps with my iPhone 11 on 5Hz Wifi.  Life was good.  However, about every 3 or 4 weeks, my download performance (directly to the cable modem) would drop to 20Mbps (upload was always within spec 24Mbps) for a few days and then would go back to 300+Mbps.  When low rebooting modem nor resetting modem to factory settings did not make a difference. 

     In Dec 2019, a Comcast tech came out and found signal coming to the property was barely within spec, replaced an outside connector, replaced the old 4-way splitter,  put a filter on the line, and replaced a connector in the house causing the noise.  After that, the performance jumped back up to 300+ Mbps and his portable device verified 1.2Gbps bandwidth.  He did say that if the problem reoccurs then he suggested a powered splitter to ensure the stability of signal levels. 

   After a few months, the problem started reoccurring every few weeks.  I bought a powered splitter and the signal levels look good but the performance still drops to 20Mbps. It has been a 20Mbps download for a week.  My SB8200  indicates the following:

 

Connection

The status listed shows the connection state of the cable modem. They are used by your service provider to evaluate the operation of the cable modem.

Startup Procedure
ProcedureStatusComment
Acquire Downstream Channel495000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
Configuration FileOK 
SecurityEnabledBPI+
DOCSIS Network Access EnabledAllowed 

 
Downstream Bonded Channels
Channel IDLock StatusModulationFrequencyPowerSNR/MERCorrectedUncorrectables
5LockedQAM256495000000 Hz-5.0 dBmV41.0 dB790
2LockedQAM256477000000 Hz-5.3 dBmV40.9 dB1040
3LockedQAM256483000000 Hz-5.4 dBmV40.7 dB870
4LockedQAM256489000000 Hz-5.2 dBmV40.8 dB990
6LockedQAM256507000000 Hz-5.0 dBmV41.0 dB750
7LockedQAM256513000000 Hz-5.4 dBmV40.7 dB1260
8LockedQAM256519000000 Hz-5.3 dBmV40.8 dB1120
9LockedQAM256525000000 Hz-5.3 dBmV40.8 dB840
10LockedQAM256531000000 Hz-5.2 dBmV40.9 dB750
11LockedQAM256537000000 Hz-5.3 dBmV40.8 dB1000
12LockedQAM256543000000 Hz-5.4 dBmV40.9 dB750
13LockedQAM256549000000 Hz-5.4 dBmV40.8 dB880
14LockedQAM256555000000 Hz-5.3 dBmV41.1 dB720
15LockedQAM256561000000 Hz-5.2 dBmV40.9 dB770
16LockedQAM256567000000 Hz-5.5 dBmV40.6 dB1300
17LockedQAM256573000000 Hz-5.5 dBmV40.7 dB1210
18LockedQAM256579000000 Hz-5.2 dBmV40.7 dB1270
19LockedQAM256585000000 Hz-5.0 dBmV40.8 dB1080
20LockedQAM256591000000 Hz-5.0 dBmV40.8 dB1470
21LockedQAM256597000000 Hz-4.8 dBmV39.1 dB1470
22LockedQAM256603000000 Hz-4.8 dBmV36.1 dB2360
23LockedQAM256609000000 Hz-5.2 dBmV39.7 dB1140
24LockedQAM256615000000 Hz-5.4 dBmV40.5 dB1110
25LockedQAM256621000000 Hz-5.6 dBmV40.5 dB1120
26LockedQAM256627000000 Hz-5.3 dBmV40.5 dB1190
27LockedQAM256639000000 Hz-5.2 dBmV40.7 dB770
28LockedQAM256645000000 Hz-4.6 dBmV40.9 dB550
29LockedQAM256651000000 Hz-4.9 dBmV40.8 dB770
30LockedQAM256657000000 Hz-4.7 dBmV40.9 dB720
31LockedQAM256663000000 Hz-4.9 dBmV40.5 dB820
32LockedQAM256669000000 Hz-5.0 dBmV40.8 dB450
37LockedOther690000000 Hz-5.2 dBmV37.8 dB3491373380



 
Upstream Bonded Channels
ChannelChannel IDLock StatusUS Channel TypeFrequencyWidthPower
11LockedSC-QAM Upstream35600000 Hz6400000 Hz39.0 dBmV
22LockedSC-QAM Upstream29200000 Hz6400000 Hz39.0 dBmV
33LockedSC-QAM Upstream22800000 Hz6400000 Hz39.0 dBmV
44LockedSC-QAM Upstream16400000 Hz6400000 Hz39.0 dBmV
59LockedSC-QAM Upstream39600000 Hz1600000 Hz39.0 dBmV



 

Current System Time: Wed Feb 17 12:28:09 2021

 

SB8200 Event Log shows a TLV 11 configuration error that has been occurring since Jan 2021 so I don't believe it is related to the 20Mpbs max download performance issue which has been occurring throughout 2020:

 

Event Log

The table below contains the log of events that the SB8200 has detected. This log can be important to the service provider to help diagnose and correct problems if any should occur.

Date Time Event ID Event Level Description
02/17/2021 11:13740101006"CM-STATUS message sent. Event Type Code: 22; Chan ID: 37; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/17/2021 11:13740101006"CM-STATUS message sent. Event Type Code: 20; Chan ID: 37; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/16/2021 10:01670616006"DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/16/2021 10:01680011023"Config File Rejected due to Invalid or Unexpected TLV 11 encoding;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/16/2021 10:01730402003"TLV-11 - Illegal Set operation failed;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:0024366940666"Honoring MDD; IP provisioning mode = IPv6"
01/01/1970 00:00820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:29680011023"Config File Rejected due to Invalid or Unexpected TLV 11 encoding;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:29730402003"TLV-11 - Illegal Set operation failed;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:2824366940443"Resetting the cable modem due to docsDevResetNow"
02/12/2021 11:24680011023"Config File Rejected due to Invalid or Unexpected TLV 11 encoding;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:24730402003"TLV-11 - Illegal Set operation failed;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:22820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:22820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:22820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:21840005003"SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:21680011023"Config File Rejected due to Invalid or Unexpected TLV 11 encoding;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:21730402003"TLV-11 - Illegal Set operation failed;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:18840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 11:16840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 10:58680011023"Config File Rejected due to Invalid or Unexpected TLV 11 encoding;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 10:58730402003"TLV-11 - Illegal Set operation failed;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 10:55840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 10:55820001003"No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 10:55840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 10:55840005003"SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 10:55840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/12/2021 10:54840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/10/2021 21:03680011023"Config File Rejected due to Invalid or Unexpected TLV 11 encoding;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/10/2021 21:03730402003"TLV-11 - Illegal Set operation failed;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
02/09/2021 21:45680011023"Config File Rejected due to Invalid or Unexpected TLV 11 encoding;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/09/2021 21:45730402003"TLV-11 - Illegal Set operation failed;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
02/09/2021 21:4424366940443"Resetting the cable modem due to docsDevResetNow"
02/09/2021 21:41680011023"Config File Rejected due to Invalid or Unexpected TLV 11 encoding;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
02/09/2021 21:41730402003"TLV-11 - Illegal Set operation failed;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00820002003"No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:01:5c:79:9c:55;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00840001003"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a4:98:13:fb:2b:8d;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
02/09/2021 21:4224366940443"Resetting the cable modem due to docsDevResetNow"

 

 

     NOTE: When the 20Mbps download speed is occurring,  I noticed that the outage map of the neighborhood next to our neighborhood indicates an issue affecting channels for subscribers, but the outage map always indicates no problem for our property in our neighborhood!

       

tracert www.comcast.net

Tracing route to e7010.dscg.akamaiedge.net [104.100.139.104]
over a maximum of 30 hops:

1 1 ms 1 ms 1 ms felidaeranch.linded.org [192.168.101.100]
2 19 ms 12 ms 9 ms 96.120.36.213
3 21 ms 20 ms 16 ms 24.153.66.65
4 13 ms 11 ms 11 ms 96.108.22.237
5 9 ms 9 ms 9 ms ae-14-ar02.stuart.fl.pompano.comcast.net [96.108.23.145]
6 12 ms 15 ms 18 ms 162.151.28.141
7 26 ms 14 ms 15 ms be-40-ar01.northdade.fl.pompano.comcast.net [68.86.165.161]
8 157 ms 22 ms 16 ms be-20214-cr02.miami.fl.ibone.comcast.net [68.86.90.205]
9 35 ms 29 ms 34 ms be-301-cr12.doraville.ga.ibone.comcast.net [96.110.38.57]
10 33 ms 36 ms 37 ms be-1312-cs03.doraville.ga.ibone.comcast.net [96.110.34.185]
11 35 ms 31 ms 33 ms be-1311-cr11.doraville.ga.ibone.comcast.net [96.110.34.170]
12 32 ms 30 ms 32 ms be-302-cr13.56marietta.ga.ibone.comcast.net [96.110.39.49]
13 33 ms 29 ms 29 ms be-1113-cs01.56marietta.ga.ibone.comcast.net [96.110.34.225]
14 33 ms 29 ms 31 ms be-2104-pe04.56marietta.ga.ibone.comcast.net [96.110.37.98]
15 31 ms 37 ms 27 ms 66.208.228.42
16 64 ms 54 ms 45 ms ae7.r02.atl01.icn.netarch.akamai.com [23.207.235.36]
17 55 ms 47 ms 42 ms ae2.r01.atl01.ien.netarch.akamai.com [23.203.144.39]
18 32 ms 31 ms 30 ms ae19.r01.border101.atl01.fab.netarch.akamai.com [23.203.144.243]
19 * * * Request timed out.
20 * * * Request timed out.
21 * * * Request timed out.
22 30 ms 28 ms 34 ms a104-100-139-104.deploy.static.akamaitechnologies.com [104.100.139.104]

Trace complete.

 

ping to www.comcast.net  

 

Ping statistics for 104.100.139.104:
Packets: Sent = 51, Received = 51, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 28ms, Maximum = 182ms, Average = 38ms

 

The 20Mbps doesn't look like an SB8200 cable modem connectivity nor performance issue between my property and Comcast network. 

 

NOTE: Comcast should suggest customer service agents not mention upgrade promotions when the customer is reporting a performance issue until the issue is resolved.  It is almost comical when the customer service agent mentions a promotion to upgrade my 600Mbps service to 1Gbps when I am can only get 20Mbps.  

 

Regards,

 

linded

 

EG
Expert

Re: Frequent 20Mbps download speed on a 600Mbps plan with SB8200 ARRIS Cable Modem

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 !



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
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ComcastBillie
Official Employee

Re: Frequent 20Mbps download speed on a 600Mbps plan with SB8200 ARRIS Cable Modem

Hello and thank you for reaching out to us here on the Forums! I can definitely understand the frustration if your internet speeds are intermittent. I would love the opportunity to help you resolve this concern and I'd like to get a look at the signal levels here on our end as well. Please click on my handle "ComcastBillie" and send us a private message with your full name and address to get started.


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Official Employees are from multiple teams within Comcast: CARE, Product, Leadership. We ask that you post publicly so people with similar questions may benefit from the conversation.
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