IPv6 works, IPv4 hasn't for days -- stonewalled by telephone support

We are experiencing an outage similar to one described in this thread: Solved: IPv6 working but not IPv4 At a high level, we first noticed that browsing most sites does not work but IPv6 enabled sites like google and facebook do. We are desperate for help as our IPv4 service has been down since April 4, 2016 at 1:24 PM and after two >30 minute calls to telephone support, I'm getting nowhere. (The rep did not even seem to understand why lack of IPv4 connectivity was a problem)

We have rebooted the modem and router dozens of times. The link layer between my modem and comcast looks good comparing the stats under http://10.1.10.1 -> Gateway Summary -> Cable Modem to those in this forum's "Connection Troubleshooting Tips". And our connection has no trouble carrying IPv6 traffic to and from the outside world:

$ ping6 -q -c 10 google.com
PING google.com(den03s10-in-x0e.1e100.net) 56 data bytes
--- google.com ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9014ms
rtt min/avg/max/mdev = 36.195/37.984/43.380/1.963 ms

The problem is with IPv4:

$ ping -c 10 75.75.75.75 -q
PING 75.75.75.75 (75.75.75.75) 56(84) bytes of data.

--- 75.75.75.75 ping statistics ---
10 packets transmitted, 0 received, 100% packet loss, time 9071ms

And the problem isn't in our local network. My v4 pings make it a few hops deep into comcast:

$ sudo traceroute -I 75.75.75.75
traceroute to 75.75.75.75 (75.75.75.75), 30 hops max, 60 byte packets
 1  10.1.10.1 (10.1.10.1)  0.336 ms  0.550 ms  0.559 ms
 2  * * *
 3  * * *
 4  te-0-2-0-1-sur02.seattle.wa.seattle.comcast.net (68.87.205.65)  10.883 ms  10.932 ms  17.134 ms
 5  * * *
 ...

I can reach this fourth hop in the traceroute over IPv4 (even over TCP) as well as my "WAN DHCP Default Gateway":

$ sudo hping3 -S 68.87.205.65 -p 80 -c 10 -q
HPING 68.87.205.65 (eth0 68.87.205.65): S set, 40 headers + 0 data bytes

--- 68.87.205.65 hping statistic ---
10 packets transmitted, 10 packets received, 0% packet loss
round-trip min/avg/max = 10.0/14.4/35.2 ms

$ ping -q -c 10 24.18.176.1 # "WAN DHCP default gateway"
PING 24.18.176.1 (24.18.176.1) 56(84) bytes of data.

--- 24.18.176.1 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9013ms
rtt min/avg/max/mdev = 7.280/9.202/14.914/2.112 ms

This makes me believe that my IPv4 packets are getting dropped somewhere inside comcast. I believe these pings are making it that far because the RTT of ~10ms to that 4th hop is way higher than the <1ms RTT across my LAN to the modem:

$ ping -q -c 10 50.245.149.186 # "WAN Internet IP Address"
PING 50.245.149.186 (50.245.149.186) 56(84) bytes of data.
--- 50.245.149.186 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9000ms
rtt min/avg/max/mdev = 0.658/0.722/0.808/0.059 ms

Comcast_John, please fix our problem for us like you did in the other thread! Thanks for reading! JC

Responses

Accepted Solution

jdcormie

New problem solver

•

4 Messages

9 years ago

FINALLY someone from comcast called me back and finally I was speaking with someone who knew what they were doing.

I gave him all the information that I posted here and in just 5 minutes he fixed it remotely by clearing out my gateway's static IP config. My "WAN Internet IP Address" is now the same as my "WAN DHCP IP Address." He couldn't explain why the gateway was incorrectly configured to use a static IP and how it could have worked for so long before suddenly failing.

For any readers suffering from the same problem, he said I could have fixed this myself with a "factory reset". You have to hold down the pin-hole button on the back of the gateway for >30 seconds. (I was only holding it down for a few seconds) There is no way for the customer to edit the static IP config through the gateway's web interface.

I'm so happy this is finally fixed BUT for those considering Comcast business, note:

- This outage was due to the misconfiguration of equiment owned by and locked down by Comcast.

- Our IPv4 was down for almost a week (!) despite daily calls to level 1 tech support.

- My case was escalated to level 2 support but rejected because "we don't troubleshoot IPv6 problems with customer equipment". They closed my ticket without informing me. Instead I had to call back and the level 1 rep read me this message.

- The solution was quick and easy for someone with the right training and access to the right tools. Good luck getting the attention of such a person! It certainly didn't happen over the phone or here on this forum.

- Speaking to the "highly talented, highly skilled" level 1 rep on day one was one of the most frustrating experiences I've ever had. She:

- didn't seem to understand what IPv4 was or why I would want it to work.

- told me that since IPv6 worked, that proved there was nothing wrong with my connection to comcast which is all that I am entitled to.

- told me "You don't have a static IP so there's nothing to troubleshoot".

- told me I should hire a local IT firm to troubleshoot because the problem is on my network.

- told me a level 2 rep would get in touch with me that same day. When I didn't hear anything for 24 hours, I called her back and she denied it saying "I didn't promise you anything". This pattern of waiting for a promised level 2 contact that never came happened two more times.

I thought I was paying more for business class tech support but this experience makes me think that money is wasted.

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jdcormie

New problem solver

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4 Messages

9 years ago

Another observation. In 10.1.10.1 -> Main -> Feature Settings -> Gateway Summary, I see two external looking IP addresses:

WAN DHCP IP Address: 24.18.185.51 (reverses to c-24-18-185-51.hsd1.wa.comcast.net.)

WAN Internet IP Address: 50.245.149.186 (reverses to 50-245-149-186-STATIC.hfc.comcastbusiness.net.)

I don't pay for a static IP address, but I think I used to. How can I clear out the "WAN Internet IP Address"? (this page does not seem editable)

Pinging my "WAN DHCP IP Address" from a working network connection, I see replies when my modem is connected and the replies stop when I unplug it. Seems like this is my correct address and the old static entry just needs to be removed.

My modem/gateway is a Netgear CG3000DCR.

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jdcormie

New problem solver

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4 Messages

9 years ago

Had an idea to test whether we are suffering from the same "IP scope had a dual assignment on the network" problem that Noel did. I unplugged our modem then pinged our "WAN Internet IP Address" from a working Internet connection:

$ ping -c 10 -q 50.245.149.186
PING 50.245.149.186 (50.245.149.186) 56(84) bytes of data.

--- 50.245.149.186 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9013ms
rtt min/avg/max/mdev = 58.221/96.196/136.501/24.211 ms

There you go -- someone else is replying at the address assigned to me by comcast ...

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DocStringer

New Member

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1 Message

7 years ago

I am having similar problems. My medical office can't run without service. This has been happening for 3 days. Need Comcast_John's help on this. All my computers that have WiFi run well on a cell phone wifi tether with my cell but nothing runs off xfinity business modem other than Google, FB, and Wikipedia that we can tell. Level 1 tech at Comcast told me to get an IT guy but why would I need my IT guy if everything works off cell phone tether on different network?

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CCMichael

Gold Problem solver

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575 Messages

7 years ago

Hello DocStringer and welcome to forums,

I apologize for my delayed response. I would like to force an IPv4 only mode to your modem to help resolve this issue. This process can take up to 40 minutes to complete and will require the modem to be rest. Would you please let me know which is the best time of day for this rest (AM|PM)

Thank You

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