Question No audio on VPN connection at work

[Nya1988]

I have an ongoing issue that I can't seem to wrap my head around. I do not have audio during real time communication when taking calls at work. The only time audio works is in Teams, however audio seems to struggle in a group teams session too.

I've had my ISP come out many times. They tell me everything looks fine, lost count of how many times they have swapped out my modem and router. I have a standard modem and a router pod. I can not get them to check the cables/wiring as their equipment is not throwing any errors. ISP is saying it could be my work's VPN that is causing the disconnect.

My work IT department has tried many different things to troubleshoot and nothing has worked. They feel it is my ISP as out of all the users who take calls, there are only 2 (which includes myself) that have the most issues and we both have the same ISP.

I am at a loss and need some guidance or recommendations. I have shown my ISP the event log from the modem. After doing research myself on the event logs and showing my IT department, it appears there is a connection loss or power loss somewhere in the cables. My ISP said that the event logs have nothing to do with the internet, it serves more like a support for the modem. Can someone please explain this? Is there truth to this or is there more that my ISP is not telling me? I have screenshots of the event logs from my modem. I can't make any changes on the modem myself either.

The screenshots don't seem to be loading...here is what I'm getting only event log.

06/05/2023 03:11	68010600​	6​	"DHCP Renew - lease parameters UTC Time Offset modified;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/05/2023 03:11	68010300​	4​	"DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/02/2023 15:11	2436694061​	5​	"Dynamic Range Window violation"
06/02/2023 15:11	82001100​	5​	"RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/02/2023 15:11	2436694061​	5​	"Dynamic Range Window violation"
06/02/2023 15:11	82001200​	5​	"RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/02/2023 15:11	67061600​	6​	"DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/02/2023 15:11	67061600​	6​	"DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/02/2023 15:11	73040100​	6​	"TLV-11 - unrecognized OID;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/02/2023 15:11	66010100​	4​	"Missing BP Configuration Setting TLV Type: 17.9;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/02/2023 15:11	66010100​	4​	"Missing BP Configuration Setting TLV Type: 17.8;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
06/02/2023 15:11	68000300​	5​	"DHCP WARNING - Non-critical field invalid in response ;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00	2436694066​	6​	"Honoring MDD; IP provisioning mode = IPv4"
01/01/1970 00:00	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
05/24/2023 07:48	84000500​	3​	"SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
05/17/2023 10:04	84000500​	3​	"SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
05/11/2023 15:00	84000500​	3​	"SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:ca:b1;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:02	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:01	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:01	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 08:26	82000200​	3​	"No Ranging Response received - T3 time-out;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:01:5c:b3:30:4b;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 08:26	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 08:26	84000200​	3​	"SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 08:26	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:25	68000100​	3​	"DHCP FAILED - Discover sent, no offer received;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:01:5c:b3:30:4b;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:25	82000200​	3​	"No Ranging Response received - T3 time-out;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:01:5c:b3:30:4b;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:25	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:20	82000400​	3​	"Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:20	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:19	82000400​	3​	"Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:19	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:19	82000400​	3​	"Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:19	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:19	82000400​	3​	"Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:19	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:18	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/25/2023 09:18	84000100​	3​	"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"
03/15/2023 10:16	84000500​	3​	"SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=5c:e3:0e:72:84:49;CMTS-MAC=00:5f:86:92:b0:ed;CM-QOS=1.1;CM-VER=3.1;"

 

[bill001g]

You are going to have to do some more detailed troubleshooting.

The sync errors are bad but they will cause all your traffic to drop and likely drop the vpn. It will not just be the audio.

Audio can be messy to get to work through a vpn. You need to see if you can get any error messages from the audio app.

One of the very common things you see with VoIP apps is related to how the ports are selected for the voice channel. These ports are negotiated in the data stream and when you have firewalls and things like NAT you need special support to open those ports.

This is kinda similar to say UPnP for games but RTP protocols need unique support.

It might not be this issue so you have to do some troubleshooting. BUT first you have to be sure that you are not completely losing your connection because of the sync errors. Sync errors are in the ISP equipment but you have to be careful it is common to see these when the modem first boots and then you don't see them after.

 

[Nya1988]

You are going to have to do some more detailed troubleshooting.

The sync errors are bad but they will cause all your traffic to drop and likely drop the vpn. It will not just be the audio.

Audio can be messy to get to work through a vpn. You need to see if you can get any error messages from the audio app.

One of the very common things you see with VoIP apps is related to how the ports are selected for the voice channel. These ports are negotiated in the data stream and when you have firewalls and things like NAT you need special support to open those ports.

This is kinda similar to say UPnP for games but RTP protocols need unique support.

It might not be this issue so you have to do some troubleshooting. BUT first you have to be sure that you are not completely losing your connection because of the sync errors. Sync errors are in the ISP equipment but you have to be careful it is common to see these when the modem first boots and then you don't see them after.

I don't get any errors within the phone software when the audio cuts out or when there is no audio. My internet connection works fine other than the audio when taking live phone calls. Could it be something is happening within the coax cable? Is the event log showing there is drop in connections? I am not sure what else I can do to troubleshoot, any suggestions would be appreciated. My ISP told me my modem is working fine.

 

[bill001g]

The coax cable/modem/router etc have no concept of audio. In addition when you run a vpn they can't even see you actual traffic. It all just looks like encrypted traffic going to the same IP.

You do not seem to be getting enough sync errors to cause a complete reboot of the modem but ever time you see that message you are getting data loss.

There should be another screen that shows your signal levels and number or error and non error packets for each channel....not sure this depends on your exact modem.

You ISP is a idiot. Technically the "modem" is fine. It is just having trouble talking to the ISP equipment in the head end. That is what the sync and no ranging respose means. These are kinda like a fancy ping command used by the modem to keep the session up with the ISP equipment. It could be caused by a cable issue but it is likely outside your house. You can check that all your connections inside your house are tight and do not have water or dirt in them. If you see signal levels issues on your modem you can try to connect it closer to where the cable comes into the house. It is not likely but bad cables or splitters can cause this.

Sync errors can also be caused by some issue in the head end equipment. It generally would affect your neighbors also.

Pretty much you are very limited to what you can test or check almost everything is outside your house.

 

[Nya1988]

Is this what you're referring to?

Procedure	Status	Comment
Acquire Downstream Channel	615000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Configuration File	OK
Security	Enabled	BPI+
DOCSIS Network Access Enabled	Allowed

Downstream Bonded Channels
Channel ID	Lock Status	Modulation	Frequency	Power	SNR/MER	Corrected	Uncorrectables
89	Locked	QAM256	615000000 Hz	2.7 dBmV	39.4 dB	0	0
74	Locked	QAM256	525000000 Hz	5.0 dBmV	39.8 dB	0	0
75	Locked	QAM256	531000000 Hz	4.6 dBmV	39.6 dB	0	0
76	Locked	QAM256	537000000 Hz	4.6 dBmV	39.8 dB	0	0
77	Locked	QAM256	543000000 Hz	4.2 dBmV	39.6 dB	0	0
78	Locked	QAM256	549000000 Hz	4.0 dBmV	39.7 dB	0	0
79	Locked	QAM256	555000000 Hz	3.7 dBmV	39.6 dB	0	0
80	Locked	QAM256	561000000 Hz	3.5 dBmV	39.6 dB	0	0
81	Locked	QAM256	567000000 Hz	3.2 dBmV	39.7 dB	0	0
82	Locked	QAM256	573000000 Hz	2.7 dBmV	39.6 dB	0	0
83	Locked	QAM256	579000000 Hz	2.7 dBmV	39.8 dB	0	0
84	Locked	QAM256	585000000 Hz	2.5 dBmV	39.6 dB	0	0
85	Locked	QAM256	591000000 Hz	2.5 dBmV	39.5 dB	0	0
86	Locked	QAM256	597000000 Hz	2.5 dBmV	39.5 dB	0	0
87	Locked	QAM256	603000000 Hz	2.6 dBmV	39.6 dB	0	0
88	Locked	QAM256	609000000 Hz	2.6 dBmV	39.6 dB	0	0
159	Locked	Other	654000000 Hz	4.0 dBmV	38.5 dB	3899833397	0
160	Locked	Other	822000000 Hz	0.0 dBmV	37.2 dB	3899833397	0

Upstream Bonded Channels
Channel	Channel ID	Lock Status	US Channel Type	Frequency	Width	Power
1	2	Locked	SC-QAM Upstream	28800000 Hz	6400000 Hz	45.0 dBmV
2	1	Locked	SC-QAM Upstream	35200000 Hz	6400000 Hz	47.0 dBmV
3	3	Locked	SC-QAM Upstream	22400000 Hz	6400000 Hz	44.0 dBmV
4	4	Locked	SC-QAM Upstream	16000000 Hz	6400000 Hz	43.0 dBmV

Current System Time: Mon Jun 5 10:34:48 2023​

 

[bill001g]

So all that all looks good. That means the sync errors are in the ISP headend

 

[Nya1988]

Thank you! How would I be able to convince my ISP that there is something going on with their end? Is it possible to have a line tech come out instead of a home tech? I have requested a line tech and they still sent out a home tech.