Very intermittent IPv6 connectivity

[Pete B]

Hi, I have an 8900AX-1600 R2 using 2.52.d5 software. I have IPv6 setup as shown in the autoconfig image attached. IPv6 connectivity is often fine for say a few minutes, then I lose it for a few minutes, then it wanders back again... the time periods are not consistent, it might be a few seconds or a few minutes... you get the picture . When IPv6 is not connected it falls back to internal IPv6 addresses only and when connected, then WAN IPv6 addresses are present too (images attached)... really as expected... but why the continuous intermittency ?
I don't really know where to start, so I'm questioning the router configuration initially, perhaps something to do with frequency of router advertisements ? I should also mention that I have a rule set up to allow IPv6 ping to pass through.

8900AX-1600R2_IPv6_autoconfig.png

The PC I'm working from is fully updated Windows 11 Pro and as such should not have issues with IPv6 but I'm not ruling out e.g. anti-virus software intererence or whatever. It's just that I feel the router is the first port of call... any ideas what might be going on here please ?

with_IPv6.png

without_IPv6.png

[Pete B]

UPDATE:
I've been able to improve this situation very significantly by using the 'other' option for IPv6 auto-config, as given in the manual. This involves disabling DHCPv6 and using RA. Disconnects decrease from every few seconds or a minute or two, to perhaps a very few per hour, which is much better. I do notice when a disconnect occurs, the output of ipconfig has an internal IPv6 address listed ahead of an external IPv6 address, or you may see just 2 identical internal addresses only. When connected, it's always an external (WAN) address listed above an internal (LAN) address. I'm afraid I don't really understand why, if configured for IPv6, any disconnects should occur as a matter of course and why IPv6 is not as solid as IPv4.

I would be grateful for any enlightenment on this subject, there might be compound issues here but I don't see what else I can change.

Thanks

[billion_fan]

UPDATE:
I've been able to improve this situation very significantly by using the 'other' option for IPv6 auto-config, as given in the manual. This involves disabling DHCPv6 and using RA. Disconnects decrease from every few seconds or a minute or two, to perhaps a very few per hour, which is much better. I do notice when a disconnect occurs, the output of ipconfig has an internal IPv6 address listed ahead of an external IPv6 address, or you may see just 2 identical internal addresses only. When connected, it's always an external (WAN) address listed above an internal (LAN) address. I'm afraid I don't really understand why, if configured for IPv6, any disconnects should occur as a matter of course and why IPv6 is not as solid as IPv4.

I would be grateful for any enlightenment on this subject, there might be compound issues here but I don't see what else I can change.

Thanks

Edit I'll run some tests here and see.

[billion_fan]

UPDATE:
I've been able to improve this situation very significantly by using the 'other' option for IPv6 auto-config, as given in the manual. This involves disabling DHCPv6 and using RA. Disconnects decrease from every few seconds or a minute or two, to perhaps a very few per hour, which is much better. I do notice when a disconnect occurs, the output of ipconfig has an internal IPv6 address listed ahead of an external IPv6 address, or you may see just 2 identical internal addresses only. When connected, it's always an external (WAN) address listed above an internal (LAN) address. I'm afraid I don't really understand why, if configured for IPv6, any disconnects should occur as a matter of course and why IPv6 is not as solid as IPv4.

I would be grateful for any enlightenment on this subject, there might be compound issues here but I don't see what else I can change.

Thanks

Edit I'll run some tests here and see.

When the issue occurs try re-applying the IPv6 autoconfig page again. Let me know if you get a proper Ipv6 address again.

[Pete B]

Yes, I've now tested your request three times and on reapplying the IPv6 auto-config settings, each time the IPv6 internet connectivity is immediately restablished with the provision of a WAN IPv6 address. It definitely seems you are on the right track with this.

[billion_fan]

Yes, I've now tested your request three times and on reapplying the IPv6 auto-config settings, each time the IPv6 internet connectivity is immediately restablished with the provision of a WAN IPv6 address. It definitely seems you are on the right track with this.

Let me check with our engineers, as of yesterday it was fine, and when I returned this morning I had no IPv6 connectivity, so lets see what they say, fingers crossed I can replicate it tomorrow.

[billion_fan]

Yes, I've now tested your request three times and on reapplying the IPv6 auto-config settings, each time the IPv6 internet connectivity is immediately restablished with the provision of a WAN IPv6 address. It definitely seems you are on the right track with this.

Let me check with our engineers, as of yesterday it was fine, and when I returned this morning I had no IPv6 connectivity, so lets see what they say, fingers crossed I can replicate it tomorrow.

I have a new firmware 2.52.d9, I'll test over the next couple of days and if IPv6 stays up I will post the fw here

[Pete B]

I have a new firmware 2.52.d9, I'll test over the next couple of days and if IPv6 stays up I will post the fw here

Well... I guess that means I'm not actually going crazy after all

[billion_fan]

I have a new firmware 2.52.d9, I'll test over the next couple of days and if IPv6 stays up I will post the fw here

Well... I guess that means I'm not actually going crazy after all

I'll leave the new firmware running until Monday, and if all goes well I will release the fw to you for testing. (so far so good 18 hours in and I still have IPv6 connectivity)

[Pete B]

Hi, I am just presuming here that you are checking the system log with this and it shows IPv6 disconnects/reconnects, if and when they happen. Perhaps you have more sophisticated logging for testing ? My system log is just a string of received RA and RS warnings, there are never any entries coinciding with dis/reconnects. I've relied on watching a Windows network status dialog while I'm working to see this instead. Disconnects are never permanent and it will always reconnect in a minute or two by itself, so there either has to be a recorded log entry to go back to or simply catch it happening in the Windows status dialog.

If you've achieved a straight 18 hours without disconnect, that's looking good already because I dis/reconnect about 3 to 4 times per hour