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IPv6 only stays up for 15 minutes at a time

I recently upgraded to the Gig service at my apartment. As part of the upgrade, I received a Technicolor TC4400 cable modem to replace my (customer-owned) SB6183. I don't recall having IPv6 issues before the upgrade, but now that I've upgraded it appears that IPv6 only works for the first 15 or so minutes after rebooting my router and modem.  I ran tcpdump from the router while pinging Google and noticed that as soon as the upstream router/CMTS sends a neighbor solicitation for my router, ping replies stop being received. This is despite my router sending the correct response back:

 

14:35:11.832550 IP6 (flowlabel 0xf3c07, hlim 63, next-header ICMPv6 (58) payload length: 16) 2606:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx > 2607:f8b0:4007:80e::200e: [icmp6 sum ok] ICMP6, echo request, seq 887
14:35:11.844035 IP6 (flowlabel 0xf3c07, hlim 55, next-header ICMPv6 (58) payload length: 16) 2607:f8b0:4007:80e::200e > 2606:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx: [icmp6 sum ok] ICMP6, echo reply, seq 887
14:35:12.292526 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::201:5cff:fe64:c046 > fe80::xxxx:xxxx:xxxx:xxxx [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has fe80::46d9:e7ff:fe9b:88ee
	  source link-address option (1), length 8 (1): 00:01:5c:64:c0:46
14:35:12.292686 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 24) fe80::xxxx:xxxx:xxxx:xxxx > fe80::201:5cff:fe64:c046: [icmp6 sum ok] ICMP6, neighbor advertisement, length 24, tgt is fe80::xxxx:xxxx:xxxx:xxxx, Flags [router, solicited]
14:35:12.831751 IP6 (flowlabel 0xf3c07, hlim 63, next-header ICMPv6 (58) payload length: 16) 2606:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx > 2607:f8b0:4007:80e::200e: [icmp6 sum ok] ICMP6, echo request, seq 888
14:35:13.837412 IP6 (flowlabel 0xf3c07, hlim 63, next-header ICMPv6 (58) payload length: 16) 2606:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx > 2607:f8b0:4007:80e::200e: [icmp6 sum ok] ICMP6, echo request, seq 889
14:35:14.842496 IP6 (flowlabel 0xf3c07, hlim 63, next-header ICMPv6 (58) payload length: 16) 2606:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx> 2607:f8b0:4007:80e::200e: [icmp6 sum ok] ICMP6, echo request, seq 890

 Could it be something with the firmware on the modem and/or something with the Gig service itself causing this issue? If so, how do I report this to Spectrum so that someone can take a look? I'm not sure I'd be able to adequately explain this issue to the people on the phone if I were to call in, especially since IPv4 works fine and the modem levels are good per the tech who installed service.

 

Thanks!

5 REPLIES
Newcomer

Re: IPv6 only stays up for 15 minutes at a time

I'm having exactly the same problem. Gig service, Modem - TC4400, Router - EdgeRouter 6p. I do get a Prefix allocation on router reboot and IPv6 works for about 5-10 minutes, then fails. Router still sees the upstream routers in the Neighbors table, Default v6 route is still present.

Community Manager

Re: IPv6 only stays up for 15 minutes at a time

@tmiw

 

If the issue is not resolved, we encourage you to contact support directly for further assistance.

 

Please contact us at: 

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Re: IPv6 only stays up for 15 minutes at a time


@James_M wrote:

@tmiw

 

If the issue is not resolved, we encourage you to contact support directly for further assistance.

 

Please contact us at: 


Thanks! The Twitter team created an escalation ticket regarding this issue so we'll see what happens.

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Re: IPv6 only stays up for 15 minutes at a time

To update: a tech came by and tried to replace the modem, with no success. I'll continue to work with the support team on a solution but I suspect it's an issue with the modem's software which will require Technicolor to resolve.

 

In the meantime I found a workaround (kill and restart the DHCPv6 service on the router every 5 minutes). Kinda ugly but at least IPv6 stays up longer than 10-15 minutes at a time.

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Newcomer

Re: IPv6 only stays up for 15 minutes at a time

I'm having the same issue on my tc4400. I also had this exact same issue on the sb8200 I had activated on ultra before. The SB6190 had no issues and would stay locked on ipv6 /56 on 3 differen vlans for weeks.