Why does the ADSL router (TP-Link D2) show a different public ip to what whatsmyip and digmyip.net show?

First number 100 right? Secondess than 64?

https://en.m.wikipedia.org/wiki/Reserved_IP_addresses

On the Router the first number is 100.

But the second number on both are higher than 64.

First number 100 right? Secondess than 64?

https://en.m.wikipedia.org/wiki/Reserved_IP_addresses

Those are unrouteable addresses. They will never be reported by web sites like whatsmyip.

First number 100 right? Secondess than 64?

https://en.m.wikipedia.org/wiki/Reserved_IP_addresses

Those are unrouteable addresses. They will never be reported by web sites like whatsmyip.

Exactly the point.

Got the less/more than 64 wrong way round but OP confirmed anyway.

Router has been assigned a carrier grade Nat as the public IP address.

What's my IP sees the true public (sharded) IP address.

Port forwarding etc impossible, but most isps will put you on a white list to not get carrier grade Nat if you ask, just need to get past 1st support line to the team that knows what this is.

First number 100 right? Secondess than 64?

https://en.m.wikipedia.org/wiki/Reserved_IP_addresses

Those are unrouteable addresses. They will never be reported by web sites like whatsmyip.

Exactly the point.

Got the less/more than 64 wrong way round but OP confirmed anyway.

Router has been assigned a carrier grade Nat as the public IP address.

What's my IP sees the true public (sharded) IP address.

Port forwarding etc impossible, but most isps will put you on a white list to not get carrier grade Nat if you ask, just need to get past 1st support line to the team that knows what this is.

I guess you are referring to CGNAT (Carrier Grade Network Address Translation).

Apparently, there seems to be some method to overcome this situation without renting a static ip from the ISP, which can be quite expensive.

Yes, carrier grade Nat as stated in the quoted post.

And the solution also stated in quoted post, ask your ISP. It's free, no need to pay and no need for static IP, public dynamic one is fine.