So I've portforwarded my machine using the graphical interface provided by my router. This interface also gives me a public IPv6 which I can use to communicate with my machine through the internet. This IP works fine, but when I check my IP on sites such as whatismyipaddress.com, the second half of my address is different. I cannot use the latter IP for communication. Why do those IP sites get the address wrong?
With IPv6 there is no need for NAT / port forwarding. The IP address you are seeing is the IPv6 address of the device you are using to access whatismyipaddress.com.
The whole idea of IPv6 is provide (bring back) end to end connectivity. NAT was only created as a short term solution for IPv4 address shortage.
There is no port forwarding for IPv6. There is only a 1:1 NAT which translates one internal address to one external address.
As you wrote
the second half of my address is different
I'd exclude 1:1 NAT from the list of possibilities.
There are three categories of routers:
- No IPv6 Support
- Allow all IPv6 traffic with out filtering. It may or should be possible to configure filter rules to some degree depending on the model.
- Drop all IPv6 traffic an require to manually setup filter rules
Please check the IP addresses on you computer using ip (Linux), ifconfig (Mac), ipconfig (Windows).
You may see multiple IPv6 addresses but one of them should be the address you see on whatismyipaddress.com.
(And please to a fresh check, some operating systems tend to change IPv6 addresses on a regular basis as a default.)