Server forgets it is running IPv6
I"ve run into a very odd IPv6 issue. I have a couple of accounts on my WHM server, each sharing an IPv4 address and having their own IPv6 addresses :):2, ::3, ::4 etc.). All DNS records are on Cloudflare"s nameservers (not in WHM).
Everything works great except about once a week when the server just forgets that it"s running IPv6 and stops responding to IPv6 requests. I solve this issue simply going to IP Functions/Assign IPv6 Address and disable and enable IPv6 for all accounts. Then everything works for about a week again.
When the issue occurs, the IPv6 addresses no longer show up in cat /proc/net/if_inet6. There are however no indications of anything wrong in WHM"s web interface. All accounts are listed green and marked enabled in IP Functions/Assign IPv6 Address.
Does anyone have an idea of what could cause this disturbance and what I can do about it?
The server is running Ubuntu v20.04.5 STANDARD kvm with cPanel 110.0.7 on a Hetzner VPS.
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Prior to when the issue occurs, has the server been rebooted? 0 -
Prior to when the issue occurs, has the server been rebooted?
Thanks for the reply. I reboot the server once or twice per month. I haven"t found any relations between the uptime and the issue. It is neither related to live-patching of the kernel.0 -
Thanks for the reply. I reboot the server once or twice per month. I haven"t found any relations between the uptime and the issue. It is neither related to live-patching of the kernel.
The reason I asked is, I've seen instances when the IPv6 range wasn't manually configured for the network adapter, after every reboot the configuration would be lost. So that may be something to look into if your IPv6 range(s) are not currently manually set.0 -
The reason I asked is, I've seen instances when the IPv6 range wasn't manually configured for the network adapter, after every reboot the configuration would be lost. So that may be something to look into if your IPv6 range(s) are not currently manually set.
Thanks. My situation is actually the opposite. Rebooting the server fixes the issue (temporarily)!0 -
Thanks. My situation is actually the opposite. Rebooting the server fixes the issue (temporarily)!
Ok, that's weird!0 -
I used to see this issue back in the day - when iPv6 stops working does this command resolve it? /scripts/restartsrv_cpipv6 Also perhaps check for any disruptions in /var/log/messages pertaining to network or ipv6, also check dmesd (before reboot) 0 -
I used to see this issue back in the day - when iPv6 stops working does this command resolve it? /scripts/restartsrv_cpipv6 Also perhaps check for any disruptions in /var/log/messages pertaining to network or ipv6, also check dmesd (before reboot)
Thanks for the reply and for letting me know that I"m not the only one who"ve run into this issue. I haven"t found any disruptions in the logs. I can however confirm that running /scripts/restartsrv_cpipv6 solves this issue. Thank you very much. Now, I can at least automate the restarts while trying to find the cause.0 -
I can't say that there's anything on the cPanel side that I've heard of that would cause this type of disruption. 0 -
I used to see this issue back in the day - when iPv6 stops working does this command resolve it? /scripts/restartsrv_cpipv6 Also perhaps check for any disruptions in /var/log/messages pertaining to network or ipv6, also check dmesd (before reboot)
When you ran into this issue, do your remember if you ran Litespeed and/or Imunify360 on your server?0 -
[QUOTE] When you ran into this issue, do your remember if you ran Litespeed and/or Imunify360 on your server?
No, it ran neither0 -
No, it ran neither
Thanks for the reply.0 -
When this happens, are your ipv6 addresses still bound to the server? You mentioned they don't show up in /proc/net/if_inet6., but if you run "ip a" do they show up there? 0 -
When this happens, are your ipv6 addresses still bound to the server? You mentioned they don't show up in /proc/net/if_inet6., but if you run "ip a" do they show up there?
Good question. I"ll check that the next time it happens.0 -
I'm not aware of anything in cPanel that would cause this, but a few things to try: - Disable imunify temporarily just to rule it out as an issue - Check any iptables-based firewalls that might be blocking ipv6 - Check sysctl.conf for any entries related to ipv6 being disabled - Are the IPs statically assigned to the server? If you're relying on DHCP to assign these IPs to the server itself, maybe DHCP is the issue? 0 -
I'm not aware of anything in cPanel that would cause this, but a few things to try: - Disable imunify temporarily just to rule it out as an issue - Check any iptables-based firewalls that might be blocking ipv6 - Check sysctl.conf for any entries related to ipv6 being disabled - Are the IPs statically assigned to the server? If you're relying on DHCP to assign these IPs to the server itself, maybe DHCP is the issue?
Thanks! I"ll do that one by one!0 -
A week ago, I found what could be a syntax error in my 99-disable-network-config.cfg file. I corrected it to the following, and so far, I haven"t lost my IPv6 support. network: {config: disabled} If you don"t see any more updates from me in this thread, this was the solution. 0 -
I'm glad you found something! 0 -
A week ago, I found what could be a syntax error in my 99-disable-network-config.cfg file. I corrected it to the following, and so far, I haven"t lost my IPv6 support. network: {config: disabled} If you don"t see any more updates from me in this thread, this was the solution.
The server has now run for a month without issues. My syntax error was the cause of the issue.0 -
Thank you for coming back and providing the solution! 0
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