Read the forum guidelines
After upgrading to SB8200, my router and modem have issues with IPv4 adresses. It begins after a period of time. Restarting the router fixes it for an indefinite period of time but eventually it loses the ability to resolve IPv4 addresses. I have tried two different routers with the SB8200, with both routers experiencing the loss of IPv4 and have not had a problem with the SB6140. This started after an upgrade to ultimate. Other forums have resolved this as a ?backend" network engineering issue but the fix is not automated. I have tried disabling IPv6 and that does not work. When IPv4 shutsdown, access to the modem address, 192.168.100.1, is affected and the modem cannot be accessed. This is not a new problem but appears unresolved in Cox as a search shows this comes up quite often. I will need to cancel the service and return the modem if this is not fixed.
First, this sounds like the opposite of what is happening to this SB8200 user. Would you be open to a different D3.1 modem?
Second, does the problem happen if you connect a PC direct to the modem?
Third, what IP subnet are you using for your router's LAN? I hear there are glitches if you use 192.168.2.1 and a couple other subnets. Not sure why, but FYI.
Last, anything in the modem's logs around the time IPv4 drops? Feel free to copy/paste the logs in the reply for review. Be sure to REMOVE your MAC address for privacy reasons.
I don't think it's related to the SB8200 user that you flagged. It is very much like http://www.dslreports.com/forum/r31767774-SB8200-losing-IPv4-connectivity-while-IPv6-works-fine and http://forums.cox.com/forum_home/internet_forum/f/internet-forum/19660/ipv4-issues-after-sb8200-upgrade---ipv6-works-fine and http://forums.xfinity.com/t5/Internet-Archive/Frequently-loosing-IPv4-while-IPv6-is-fine/td-p/2923874.
I have not noticed the problem with direct connection but that could be due to time as I don't have the option of keeping a computer connected without a router. The problem occures with multiple routers. The telltale sign is traceroute works to IPv6 addresses while failing IPv4 addresses. Even the modem interface 192.168.100.1 becomes unroutable while google is fine.I use 192.168.1.1. For one of the routers I tried, that's the default subnet. Another uses 192.168.0.1 as the default. Both work fine until it starts dropping IPv4 routes.
There is nothing in the logs, other than reboots. I have power numbers and S/N rations will within spec and the modem looks fine from Cox's end.
I will read those threads and do some brainstorming and post later tonight with more.
First thing that comes to mind is to check the DHCP lease time. It can be anywhere from 2 hours to 48 hours, and if that timeframe and your problem match, it's probably related. Could also try setting your DHCP IP as a static IP and see if that makes the problem go away. Wouldn't be a long term solution, but would help isolate the issue.
LAN DHCP is unrelated. It's related to how Cox routes IPv6 addresses and how it updates route tables and apparently how that information is fed to the modem's route table.
Here is a tracert to "gmail.com" when the modem is working and when it fails. The issue is outside the local lan but is at a crossover to IPv6 in Cox land and is part of the route table that the modem stores. Rebooting the modem "fixes" it until some IPv6/IPv4 route table update from an access corrupts the routing table and makes everything unreachable including the mode @ 192.168.100.1. Probably accessible to tech that can arp the modems route table.
Working, no isues...C:\Windows\system32>tracert gmail.comTracing route to gmail.com [22.214.171.124]over a maximum of 30 hops: 1 1 ms <1 ms 1 ms 192.168.1.1 2 7 ms 8 ms 8 ms 10.39.120.1 3 9 ms 8 ms 8 ms 100.127.73.172 4 8 ms 8 ms 8 ms 100.120.100.6 5 20 ms 20 ms 20 ms 126.96.36.199 6 20 ms 20 ms 21 ms 188.8.131.52 7 * * * Request timed out. 8 23 ms 22 ms 21 ms 184.108.40.206 9 20 ms 20 ms 21 ms 220.127.116.11 10 20 ms 21 ms 20 ms lax28s01-in-f5.1e100.net [18.104.22.168]Trace complete.Broken - (Modem IP 192.168.100.1 as well as all others are unreachable when in this state)C:\Windows\system32>tracert gmail.comTracing route to gmail.com [22.214.171.124]over a maximum of 30 hops: 1 1 ms 2 ms <1 ms 192.168.1.1 2 8 ms 8 ms 8 ms 10.39.120.1 3 9 ms 8 ms 8 ms 100.127.73.174 4 10 ms 8 ms 8 ms 100.120.100.10 5 118 ms 117 ms 22 ms 126.96.36.199 6 ip72-221-28-166.ph.ph.cox.net [188.8.131.52] reports: Destination host unreachable.Trace complete.