IPv6 on a TP-Link ER605 router

[#1]

@zpeterk wrote: Have you set any ACL rules to get it to work?

No.

I think the default behavior seems to be the same as for IPv4 -

All incoming connections from WAN are dropped.

Outbound traffic to the WAN is allowed.  

Traffic is routed between the (non WAN) VLans (I assume I can add access control rules to stop that but have not yet tried to do so.)

My setup for IPv6 was

1. Configure the WAN (as your post 8 ) 

2. Configure the LAN (as in my first post) As part of that I think I had to enable the prefix delegation server and add an entry.

Then my windows 10 and 11 PCs would connect - 

Android phone, iPhone and iPad also pick up IPv6 addresses, though were slow to do so but I think that may be due to a problem with my home network.

[#2]

Here's a screenshot of my IPv6 LAN page after configuration.

[#3]

@IMM 

Thanks for that, all working now, but only one WAN at a time.

[#4]

I only have one WAN - so cannot try anything out. 

However If you have more than 1 Vlan, I wonder whether you could delegate one WAN to Vlan1 and another WAN to Vlan2 etc.

Similarly, once it is initially set up, I wonder whether you can add entries to the prefix delegation server so that more than one WAN delegates to each Vlan

I'll have to let you experiment with that as I can't.

[#5]

For IP6 with multiple WAN links, you have to be careful to ensure that the right IP addresses go to each WAN.

If WAN1 gives you aa:bb:cc:dd::/YY and WAN2 gives you ee:ff:gg:hh::/ZZ then usually you can't send WAN1's traffic over WAN2 and vice-versa as the providers have anti-spoofing rules in place.

That isn't usually an issue for IP4 traffic as that's usually handled by NAT.

I'm not familiar with this particular device's capabilities, but you handle this using 'policy based routing' on Linux systems.

[#6]

Well I asked the question on the TP Link bussiness forum and the reply is that although advertised a a multi WAN load balancing  IPv6 router it can only cope with one IPv6 WAN which makes it pretty useless.

[#7]

t would appear the router can't cope with two IPv6 wans as the PD has to be specified in the lan settings and therefore can't fall back to the other wan in the event of failure.

@zpeterk seems that NPt (Network prefix translation) is one method of handling multiple IPv6 WANs

pfSense claims to support it https://docs.netgate.com/pfsense/en/latest/recipes/multiwan-ipv6.html but I would guess that the TPlink firmware doesnt.

Looks like there's still generally a lot of work needed in the multi WAN IPv6 scenario....

edit: there's an interesting thread in the Openwrt forums here https://forum.openwrt.org/t/ipv6-wan-fail-over-without-ipv6-nat/146403/66 .

A bit of a 'kludge' which works by changing the prefix lifetimes..

[#8]

That's a very useful thread from the OpenWRT forum that does cover most of this, MisterW.

Ultimately for dual stacked clients, if your IP6 connection dies, at least IP4+NAT will maintain your connectivity and pretty much every tcp ip implementation handles 'IP6-unavailable but IP4 working' decently well.

Client behaviour for multiple IP6 addresses assigned, one of which is not working isn't something I've tested to any great degree.  However, when I was running with 5G primary + fttc secondary, I did just announce IP6 addresses from both to clients, alongside IP4 internal addressing, and I never noticed anything particularly horrible when one or other link went down or came back.