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Robert-Earl's avatar
Robert-Earl
Aspirant
Apr 06, 2026

Brittle, fragile IPv6 connectivity: often breaks with time and without being touched

Greetings,

 

Today, we tweaked one or two IPv6 settin" gs on my RS300, and we noticed that it was already malfunctioning. We were unsure whether "RIPng" was a necessary setting.

 

However, we have often observed that IPv6 stops working: that is, for client devices on the inside of my LAN on a normal ISP connection, they lose their unique globally-routed IPv6 assignments and Network Prefix. There is no particular reason for this that we've been able to discern.

 

 

The Netgear router is typically configured to "Auto Config" under the Advanced-> IPv6 settings. But it also often loses the "Router IPv6 address on WAN" and/or "Router IPv6 address on LAN" for no reason. Our workaround for this is usually to tweak the "Auto Detect" setting to "Auto Detect" or off/then on, or something else, briefly "Apply" and then revert to the settings which had originally worked. 

 

Our ISP appears to not have implemented DHCPv6. Therefore the DHCPv6 settings were non-functional. However, SLAAC is typically functional, and it is the usual way we obtain the Network Prefix delegated from ISP. 

 

Furthermore, if anyone knows a way to easily do introspection on IPv6 and IPv4 WAN addresses, please let us know. Formerly, we used English Wikipedia, or Meta or Commons while logged out, but that doesn't work due to their privacy restrictions now. "whatismyipaddress dot com" is clogged with nearly malicious ads and streaming video that bombard us as soon as we visit that site. We cannot find any IPv6-capable tools on dynu.com, which is a really good site otherwise!

3 Replies

  • FURRYe38's avatar
    FURRYe38
    Guru - Experienced User

    Whos your ISP?

    What Firmware version is currently loaded?

    What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected too?

     

    Using ISP detected IPv6 DNS or custom IPv6 DNS?

     

    Be sure to test any IPv6 configurations out here: 

    test-ipv6.com

     

    Robert-Earl wrote:

    Today, we tweaked one or two IPv6 settin" gs on my RS300, and we noticed that it was already malfunctioning. We were unsure whether "RIPng" was a necessary setting.

     

    However, we have often observed that IPv6 stops working: that is, for client devices on the inside of my LAN on a normal ISP connection, they lose their unique globally-routed IPv6 assignments and Network Prefix. There is no particular reason for this that we've been able to discern.

     

     

    The Netgear router is typically configured to "Auto Config" under the Advanced-> IPv6 settings. But it also often loses the "Router IPv6 address on WAN" and/or "Router IPv6 address on LAN" for no reason. Our workaround for this is usually to tweak the "Auto Detect" setting to "Auto Detect" or off/then on, or something else, briefly "Apply" and then revert to the settings which had originally worked. 

     

    Our ISP appears to not have implemented DHCPv6. Therefore the DHCPv6 settings were non-functional. However, SLAAC is typically functional, and it is the usual way we obtain the Network Prefix delegated from ISP. 

     

    Furthermore, if anyone knows a way to easily do introspection on IPv6 and IPv4 WAN addresses, please let us know. Formerly, we used English Wikipedia, or Meta or Commons while logged out, but that doesn't work due to their privacy restrictions now. "whatismyipaddress dot com" is clogged with nearly malicious ads and streaming video that bombard us as soon as we visit that site. We cannot find any IPv6-capable tools on dynu.com, which is a really good site otherwise!

     

  • plemans's avatar
    plemans
    Guru - Experienced User

    Not srue who your ISP is but Xfinity's DNS for IPv6 has had issues. Use a different DNS provider. 

    Mine is stable when its not on xfinity's. 

  • I don't have any issues with Xfinity ISP and ipv6 with my RS500 router, although ipv6 feels a bit slower with Xfinity. Auto detect show detect the type of ISP connection in use. Xfinity uses DHCPv6 with prefix delegation.