Yeah hearing that is the final straw for me, I thought TP-Link was a reliable brand, obviously not.
I'm gonna try get this garbage returned to amazon, along with their awfully glitchy Tapo bulbs.
Don't touch TP-Link with a barge pole!
Oh and I almost forgot, thank you @licquorice and @Crimliar for trying to assist.
The TP-Link being incompatible with a /56 prefix is completely bonkers! I'd been under the impression that most routers would take any prefix that was a multiple of 8!
If you do switch to an Asus router I'd suggest an RT-AX86u or better if you intend to run the AsusWRT-Merlin firmwares that are popular. I only have the GT-AX6000 because a week after launch I got it "open box" from work having been used for product shots!
Oh it's definitely borked, the WAN IPv6 Address kept jumping from fe80 to 20 something.
Bonkers, all TP-Link support has to say is "it is supported", evidently not as I've found others online with the exact same problem.
It's not like IPv6 is behind some sort of lock and key, ludicrous.
To be honest I don't really have a need for IPv6 other than the occasional gaming session, so I'm still undecided as to whether I should get another router or not (I should for future proofing reasons really).
There is useful features like VPN Client and Server I'm making use of, it doesn't support Dns-over-HTTPS though resulting in me having to buy another Pi (set up today), for failover AdGuard Home and the whynot secure it factor, probably wouldn't have bought that if my router was any good lol.
I do also like the Wi-Fi speeds as I'm primarily on a laptop and do file transferring, having my own dedicated 5GHz band was partly the main appeal of this one (and not being locked out of all the settings like on the BT hub).
Returned 11 TP-Link Tapo devices today, good riddance. lol
IPv6 addresses starting FE80 are local addresses, while the 20xx: ones you've seen should be fully addressable (subject to firewalls) from the internet.
FYI: I have Tapo bulbs, dimmers, switches, and sensors, all of which work perfectly!
Set them to auto mode and have a custom on state set with the brightness above 80%.
Enjoy pulling your hair out when you power cycle them and they dim for 60 seconds or Flash when you first send a command to them and Gradual fade is enabled.
My main use case was the adaptive/auto lighting (orange of a night, blue of a day), TP-Links own one caused them to drop to like 6% brightness for 60 seconds when toggled at the power.
Home-assistant/the app causes them to flash on the first command.
Rubbish. TP-Link support proved to be useless at resolving the matter.
Probably a topic for a different thread, but I agree the "adaptive" setting doesn't work, but as we have bright orange walls (way less garish than it sounds) having them on a fixed very warm white has always been best.
I'll admit that I don't understand too much of this thread but I did notice in message 22 that the username for the IPv6 side was @btinternet.com not @btbroadband.com
Relevant or not I don't know.
I believe the RT-AC88u is now EOL, and it's always had what can be a problematic issue. There's a bridge between the first 4 LAN ports and the second 4 LAN ports that tends to fail. The solution for many users has been, not to use LAN ports 5-8!