> Very happy to be told why I shouldn't do this though.
Because your IPv4 traffic goes (or will, in the future, as IPv4 depletes further) through a slow, overprovisioned CGNAT - making IPv4 much slower then IPv6.
That's scaremongering and simply false. Cgnat servers are not necessarily congested. I've been to several isps with cgnat and none of them suffered from congestion.
On a more personal note, if ipv6 were so great, their fans wouldn't have to make up things to badmouth ipv4.
NAT is fundamentally a limited technology that has massive scaling problems that simply do not exist in non-nat networking situations.
The larger the network behind the NAT, the more problems you get. This is also before considerations like the fact NAT breaks 2 way connectivity that is the cornerstone of the design of the internet.
>if ipv6 were so great, their fans wouldn't have to make up things to badmouth ipv4.
The explicit goal and reason IPv6 was created was to make up for the short-comings of IPv4.
The Internet of the 1990s was very different to the Internet of 2020. The widespread surveillance of activity as it exists today was not a consideration back then, nor were there the same security concerns, making it a desirable property to have every device uniquely and globally addressable.
Privacy extensions were then ratified (RFC 4941) after 2007 as a workaround, and firewalls get applied on hosts and gateways to protect against bad actors on the Internet (which are significantly more prevalent today than 20+ years ago).
IPv6 is not a magic bullet. The increase in addressable space is definitely a positive. Pretty much everything else is up for debate, depending on perspective and use case.
I've been dual-stacking networks for over a decade. The easy part[0] is making the network work with both IPv4 and IPv6. The hard part is making everything else work.
[0] Easy is relative. I agree with everything listed in https://news.ycombinator.com/item?id=24059729 as additional sources of complexity and confusion. That's still just the mole hill at the start of the mountain.
> I've been to several isps with cgnat and none of them suffered from congestion.
And I've been on several residential ISPs where IPv4 was unusable during peak netflix hours, likely because people were blindly disabling IPv6 on their devices.
I had to disable IPv6 for Netflix because Netflix has decided that the IPv6 address space I get from Hurricane Electric and the IPv6 address space my wireline ISP hands out are both "VPNs" and blocks them.
With AAAA enabled for *.netflix.com address resolution, I can't watch Netflix. If I actually paid for it, versus getting it included as a perk of T-Mobile, I'd have quit over that. I shouldn't have to fiddle with DNS to watch a service I pay for.
That's not necessarily a problem with nat; anybody with basic networking knowledge can tell you that packets that move through v4 and V6 do not have to follow the same routes. Since there are more users using v4 than V6 it's common for v4 routes to be congested while V6 routes are not.
Because your IPv4 traffic goes (or will, in the future, as IPv4 depletes further) through a slow, overprovisioned CGNAT - making IPv4 much slower then IPv6.