2x Google WiFis and IPv6

[fulito]

2 Google Wifis

• 1st connected to ISP router using DHCP, but I also tried using PPPoE with the same results.
• 2nd connected to the 1st one using ethernet.

Modes

• 1st Google Wifi is in NAT mode, so that
• 2nd Google Wifi is in bride mode and
• both provide seamless wifi access points

All great with IPv4. Does not work with IPv6. It does not seem to get an IPv6 from the ISP or announce IPv6 to the internal network, I didn't see any RA traffic.

I read somewhere that the reason for this is 1st Wifi working in NAT mode, which is a requirement for having a 2nd one and for most of the Google Wifi features.

Is this true?

Please note that IPv6 works perfectly for devices connected directly to the ISP router.

Thanks,

Julio

[MichaelP · Accepted solution]

I ran IPv6 successfully for many years on Google WiFi, with one primary (router+firewall "NAT" mode) plus two wired secondaries ("bridge" mode). The secondaries are irrelevant here – they're just transparent bridges and aren't involved in getting IPv6 to work.

The key is getting your primary (router/firewall mode) Google WiFi unit to receive an IPv6 prefix delegation from the upstream router it's connected to. I did that by connecting to my cable provider through a simple cable modem (not a combination modem+router+firewall). So, it's "upstream" router was my ISP's head end cable router.

If you are connecting through an existing on-premises ISP router (which it sounds like you are), then that router would need to be configured to provide a prefix delegation (not just individual host IPv6 configuration) through DHCPv6. It sounds like it is getting a prefix delegation from the ISP, but it would need to provide a longer prefix to your "inner" router.

Most ISP-provided routers are not capable of this. Basically, if you have double-NAT for IPv4, you are unlikely to get an IPv6 prefix delegation (it's not 100% impossible, depending on how configurable that ISP router is). But, if you can get that ISP-provided router out of the picture (or into bridge mode, if it's a combination modem+router+firewall), then you may be able to get an IPv6 prefix delegation directly from your ISP.

[fulito]

Thanks! That gives me hope to keep trying.

Yes, I am using a "mandatory" ISP router. I say "mandatory" because it is in part (that router connects to fiber optic network and Google Wifi does not) but also has a "bridge" mode that definitely removes double-NAT and could reduce any incompatibilities between the two. I guess I could try the route of replacing that ISP router with another one with that capabilities but that is out of scope because getting IPv6 in my home network is not critical enough.

I did try that bridge mode, but with a couple of caveats: one, not hard enough. Second, it is not a "pure" bridge mode, it is something intermediate as described by people that seem very knowledgeable in that particular router and ISP. Their claims are that I would be able to use prefix-delegation even when not in that pseudo-bridge mode. That pseudo-bridge mode removes NAT and allows Google Wifi to use PPPoE to get a "direct" internet connection to the ISP, which seems what you described. I think I did not try hard enough because there are a set of parameters in that ISP router that could still be affecting the setup that I did not try, and I will.

I will try and report back if I find anything interesting.

Thanks!

Julio

[fulito]

Well, I tried everything I said without success. Experimented with ISP router parameters, also after enabling bridge mode and pppoe. Nothing seems to work. I found one forum thread in a spanish forum claiming that support was disabled in 2018 with a link to the corresponding firmware update, but that date is not available anymore in the changelog.