I know that IPv6 was created in 1998 as a future-proofing, to make sure that there will be enough IP addresses in the works for large networks. IPv4 uses 32 bits and is represented with denary (0-9) while IPv6 uses 128 bits, so there are far more possible addresses, and it is represented using hexadecimal (0-9 then A-F).
What I’m wondering is why IPv4 is still so common, even though the number of devices connected to the internet have skyrocketed with more computers, laptops, smartphones, game consoles, embedded systems, etc. all connected! If it was thought that there would be too few available addresses in 1998, surely that has to be a bigger problem in the modern day?
Additionally, why didn’t IPv6 replace v4, even after nearly three decades of existing? Is it a technological limitation, cost, or something else?
And online I see many sysadmins online (!) complaining about IPv6 being more difficult to work with. Is this because the addresses are harder to remember, are adaptations of the protocol by manufacturers all different (similar to USB-C), or is there some other problem with IPv6? Or is this a case of a loud angry minority, especially in chat forums where people tend to have more polarised views?
Many devices do support IPv6, but it’s not universal like IPv4, despite the standard existing since 1998 and having many advantages. Why is this?


I was going to point that out as well.
Your phone is probably on an IP6 network right now.
And it will be NATted to an IP4 address when it leaves the carrier’s network to interact with the public internet.
Does that mean you can use IP6 to connect despite CGNAT, or do the ISPs that use it tend to firewall off the IP6 connections anyway?
If your ISP supports IPv6, then yes, you can use IPv6 to get a publicly reachable address when you would otherwise be unable to due to being behind a CGNAT. If your ISP does not support IPv6, you are out of luck. There are methods to translate between IPv4 and IPv6, but they require a public IPv4 address.
My friend switched to Starlink recently and was disappointed to find out he can’t host Minecraft servers and such due to CGNAT. Luckily, Starlink does support IPv6, so he was able to host his servers that way. The caveat is that we have to be IPv6 capable to join his server.