I've had my SB8200 about a month with Cox ISP and have a recurring problem where IPv4 stops working but IPv6 is fine. I can only access websites that have AAAA records in DNS with an IPv6 address. Restarting modem fixes issue - restarting my Netgear Orbi router doesn't help. Prior to SB8200 I had a Netgear CM600 and never had this issue. I don't have an OFDM channel yet, my SB8200 modem is connected on 32 downstream and 4 upstream channels.
I telnetted into my Netgear Orbi router to do some troubleshooting. Everything looks good
root@RBR50:/# route -nKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Iface0.0.0.0 174.66.192.1 0.0.0.0 UG 0 0 0 brwan174.66.192.0 0.0.0.0 255.255.248.0 U 0 0 0 brwan192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 br0239.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 br0
Redacted my specific IP (xxx)
root@RBR50:/# ip route default via 174.66.192.1 dev brwan 174.66.192.0/21 dev brwan proto kernel scope link src 174.66.196.xxx192.168.1.0/24 dev br0 proto kernel scope link src 192.168.1.1 239.0.0.0/8 dev br0 scope link
root@RBR50:/# ip -6 route 2600:8806:8200:1b::/64 dev br0 proto kernel metric 256 2600:8806:9f00:200:2889:2343:2702:592b dev brwan proto kernel metric 256 fe80::/64 dev eth1 proto kernel metric 256 fe80::/64 dev eth0 proto kernel metric 256 fe80::/64 dev ath0 proto kernel metric 256 fe80::/64 dev ath1 proto kernel metric 256 fe80::/64 dev ath2 proto kernel metric 256 fe80::/64 dev ath01 proto kernel metric 256 fe80::/64 dev brwan proto kernel metric 256 fe80::/64 dev br0 proto kernel metric 256 default via fe80::6600:f1ff:fe3f:efd9 dev brwan metric 1
root@RBR50:/# cat /etc/resolv.conf nameserver 68.105.28.11nameserver 68.105.29.11nameserver 68.105.28.12nameserver 2001:578:3f::30 nameserver 2001:578:3f:1::30
Did some ping tests. I cannot ping default gateway 174.66.192.1 from my computers or from the router itself.
I can ping IPv6 hosts out on the internet just fine, can't ping IPv4 hosts:
root@RBR50:/bin# ping6 e16.ycpi.nya.yahoo.comPING e16.ycpi.nya.yahoo.com (2001:4998:1c:803::2003): 56 data bytes64 bytes from 2001:4998:1c:803::2003: icmp6_seq=0 ttl=58 time=33.9 ms64 bytes from 2001:4998:1c:803::2003: icmp6_seq=1 ttl=58 time=41.1 ms64 bytes from 2001:4998:1c:803::2003: icmp6_seq=2 ttl=58 time=33.8 ms64 bytes from 2001:4998:1c:803::2003: icmp6_seq=3 ttl=58 time=33.4 ms64 bytes from 2001:4998:1c:803::2003: icmp6_seq=4 ttl=58 time=33.5 ms64 bytes from 2001:4998:1c:803::2003: icmp6_seq=5 ttl=58 time=33.2 ms^C--- e16.ycpi.nya.yahoo.com ping statistics ---6 packets transmitted, 6 packets received, 0% packet lossround-trip min/avg/max = 33.2/34.8/41.1 ms
root@RBR50:/bin# ping e16.ycpi.nya.yahoo.com PING e16.ycpi.nya.yahoo.com (69.147.82.219): 56 data bytes
The IPv4 ping test seems to be resolving via ipv6 resolvers based on how long it took to resolve. I feel like it timed out on the three v4 resolvers in /etc/resolv.conf before hitting ipv6 resolvers and getting a v4 IP address back from v6 resolver.
So at this point, I restarted my router. Didn't help anything. GUI said it couldn't connect to internet. So I restarted my modem, and then it worked! Routing tables on the router and resolv.config looked identical after restarting modem - I received same IP address from Cox.
I've had this particular IPv4/IPV6 issue happen about 4 times over course of ownership of this modem (so weekly). Each time, restarted modem fixes. This last time I didn't even both restarting router. I wonder if this is related to this other problem I have with SB8200 where I can't access admin page: https://www.dslreports.com/forum/r31725961-Modem-Admin-page-blocked-on-my-SB8200
I called ARRIS first, they said there is nothing to configure on modem so nothing to do other than call Cox. Called Cox, they didn't really have any ideas either. Said call next time it happens.
I found similar complaints on Comcast forum (I have Cox service) from both users of the SB8200 and MB8600 (same chipset):
http://forums.xfinity.com/t5/Your-Home-Network/Frequently-loosing-IPv4-while-IPv6-is-fine/td-p/2923874
http://forums.xfinity.com/t5/Your-Home-Network/Re-Frequently-loosing-IPv4-while-IPv6-is-fine/td-p/3016461
http://forums.xfinity.com/t5/Your-Home-Network/Motorola-MB8600-frequently-loses-IPv4-connection-but-IPv6-is-ok/td-p/2996458
Anyone else experiencing this?
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