Connection issues with VRChat (RG crash, Packet loss?)

[Bamber_FM]

When playing VRChat I will consistently be unable to receive any in game notifications.
Also on joining any high population instances, my router will almost immediately crash stating

Cable Modem Reboot due to RG crash

Spoiler

Network Log

Time Priority Description

10-04-2023 21:47:17	notice	REGISTRATION COMPLETE - Waiting for Operational status
10-04-2023 21:47:10	notice	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
10-04-2023 21:46:57	warning	DHCP WARNING - Non-critical field invalid in response ;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
10-04-2023 21:46:55	notice	Honoring MDD; IP provisioning mode = IPv4
10-04-2023 21:46:49	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
10-04-2023 21:46:37	critical	Cable Modem Reboot due to RG crash
10-04-2023 21:36:34	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
10-04-2023 21:36:29	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
10-04-2023 21:36:17	critical	Cable Modem Reboot due to RG crash
04-04-2023 08:02:44	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-04-2023 08:02:40	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-04-2023 08:02:28	critical	Cable Modem Reboot due to power button reset
04-04-2023 02:50:00	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-04-2023 02:49:54	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-04-2023 02:49:47	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-04-2023 02:49:40	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-04-2023 02:49:27	critical	Cable Modem Reboot due to SW Upgrade

Spoiler

General Configuration

Network accessMaximum Number of CPEsBaseline PrivacyDOCSIS ModeConfig file

Allowed

1

Enabled

3.1

cmreg-vmdg660-bbt062-b.cm

Primary Downstream Service Flow

SFIDMax Traffic RateMax Traffic BurstMin Traffic Rate

2032

402500089 bps

42600bytes

0 bps

Primary Upstream Service Flow

SFIDMax Traffic RateMax Traffic BurstMin Traffic RateMax Concatenated BurstScheduling Type

2031

38500089 bps

42600bytes

0 bps

42600bytes

Best Effort

Spoiler

Upstream bonded channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

0	60300000	35	5120	QAM 64	1
1	53700000	35.3	5120	QAM 64	2
2	46200000	35.3	5120	QAM 64	3
3	39400000	35.3	5120	QAM 64	4
4	32600000	35.5	5120	QAM 64	5
5	23600000	35.5	5120	QAM 64	10

Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

0	ATDMA	0	0	0	0
1	ATDMA	0	0	0	0
2	ATDMA	0	0	0	0
3	ATDMA	0	0	0	0
4	ATDMA	0	0	0	0
5	ATDMA	0	0	0	0

Spoiler

Downstream bonded channels

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

1	139000000	3.1	41	QAM 256	1
2	147000000	3.1	41	QAM 256	2
3	155000000	3.1	41	QAM 256	3
4	163000000	3.1	41	QAM 256	4
5	171000000	3.2	41	QAM 256	5
6	179000000	3.3	41	QAM 256	6
7	187000000	3.4	40	QAM 256	7
8	195000000	3.5	41	QAM 256	8
9	203000000	3.5	41	QAM 256	9
10	211000000	3.4	41	QAM 256	10
11	219000000	3.6	41	QAM 256	11
12	227000000	3.7	41	QAM 256	12
13	235000000	3	41	QAM 256	13
14	243000000	3.7	41	QAM 256	14
15	251000000	3.3	41	QAM 256	15
16	259000000	3.4	41	QAM 256	16
17	267000000	3.4	41	QAM 256	17
18	275000000	3.4	41	QAM 256	18
19	283000000	3.2	41	QAM 256	19
20	291000000	3.2	40	QAM 256	20
21	299000000	3.2	40	QAM 256	21
22	307000000	3.2	40	QAM 256	22
23	315000000	3	40	QAM 256	23
24	323000000	2.9	40	QAM 256	24
25	331000000	2.7	40	QAM 256	25
26	339000000	2.8	40	QAM 256	26
27	347000000	2.7	40	QAM 256	27
28	355000000	2.7	40	QAM 256	28
29	363000000	2.7	40	QAM 256	29
30	371000000	2.8	40	QAM 256	30
31	379000000	2.8	40	QAM 256	31

Downstream bonded channels

Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors

1	Locked	41	4	0
2	Locked	41	6	0
3	Locked	41	7	0
4	Locked	41	7	0
5	Locked	41	8	0
6	Locked	41	8	0
7	Locked	40	17	0
8	Locked	41	14	0
9	Locked	41	27	0
10	Locked	41	29	0
11	Locked	41	33	0
12	Locked	41	32	0
13	Locked	41	37	0
14	Locked	41	36	0
15	Locked	41	56	0
16	Locked	41	50	0
17	Locked	41	65	0
18	Locked	41	64	0
19	Locked	41	103	0
20	Locked	40	114	0
21	Locked	40	157	0
22	Locked	40	162	0
23	Locked	40	212	0
24	Locked	40	248	0
25	Locked	40	299	0
26	Locked	40	353	0
27	Locked	40	444	0
28	Locked	40	490	0
29	Locked	40	572	0
30	Locked	40	611	0
31	Locked	40	760	0

[IPFreely]

Thank you. 

04-04-2023 02:49:27 your presumably Hub 5 received a software update. 6 days later it started crashing.

You aren't the only person seeing these issues: looks like there's a software problem with the Hub 5 causing it to reboot when certain patterns of data go through it.

The same model was experiencing crashes in the Netherlands however they seem to think they fixed it with a software change.

I'm not sure if that's been done in the UK as well, making this a new issue, or if the software you downloaded and presumably the other customer has is actually the cause of the problem and it's introduced the same issue Ziggo customers in the Netherlands had while previous software didn't have it.

Either way it seems almost certain it's a software problem with the Hub 5. Good luck with the forum team. You'll need it. 

[Bamber_FM]

Does setting the Hub to modem only and using a separate router have any history of solving these issues? Or will the issues continue regardless.

[IPFreely]

According to the other recent poster with these issues modem mode doesn't help. 

https://community.virginmedia.com/t5/Gaming-Support/SYNC-Timing-Synchronization-failure-while-in-vr/...

[Adri_G]

Hi Bamber_FM, thank you for joining the help forums and welcome to our community.

Sorry to hear of the issues with gaming on VR recently and the errors you've faced, we'd love to best assist with this.

Upon our most recent checks, the overall service and connections seem to work excellent at the minute from this end.

However, as you've experienced disconnections due to the hub rebooting and the errors you got we'll need to investigate things a bit further.

Can you please advise which console you're using when on VR gaming and if that connects via ethernet or wireless?

Are there more consoles in use at the time when the issue with the hub crashing occurred or other heavy users?

Lastly, have you tried a pin-hole reset on the hub (as seen here) to see if this will rectify the issue?

Please, share more so we can assist further.

[eth0]

I've been having exactly the same issue!

Full details in this thread: https://community.virginmedia.com/t5/Networking-and-WiFi/Hub-5-crashes-from-RTSP-stream/m-p/5307855/...

But in short:

It's an issue with the Application Level Gateway (ALG) in Hub 5 firmware LG-RDK_4.6.24-2206.7

When you're in a VRChat world with an RTSP stream in the background for music, the ALG crashes and kernel panic's the router

The crash can be replicated with a simple Linux command

echo "SETUP A" | nc portquiz.net 554

There will be no proper fix until Virgin's engineers patch and deploy a new firmware version. But there are 2 short-term fixes:

Block 445 Outbound:

In your router admin page: Advanced Settings > Security > IP and Port filtering > Create a new rule
The rule should then be set to:

Source address: All, Destination address: All, Protocol: TCP, Source port: All, Destination port: 554, Enabled (checked)

This will simply stop any RTSP streams from being established. In VRChat specifically you will lose world music, but everything else should keep working.

VPN:

Another option is to just use a VPN so the router can't see the RTSP traffic at all, so the ALG is never triggered. For normal streams any VPN type would be fine, but for VRChat you'll probably need something with minimal overhead like the Wireguard protocol.

Hopefully this helps :)!

[Lisa_CC]

Hi @Bamber_FM 

We've been looking into this issue that was reported on a different thread and our back office Team are unable to replicate the connection drop. Please provide the actual RTSP stream URL that causes the drop so we can continue with our investigation.

Thanks,

Lisa

[Bamber_FM]

"rtspt://stream.vrcdn.live/live/thorinair"
Play this in any VRChat world with a video player that can load streams (Most Can) on the Hub 5.
The Hub 5 will Reboot due to RG crash.
[I have; Hardware version:1.2 / Software version: LG-RDK_4.6.24-2206.7]

[Paulina_Z]

Hi @Bamber_FM,

Thanks for coming back to us and for providing the needed details!

We've passed the information onto the dedicated team to continue the investigation to resolve this issue.

Thank you! 😊 

[Lisa_CC]

Hi,

Thanks for being patient with us. We've managed to replicate the issue and have raised a bug for it.

Regards,

Lisa