New fiber internet and port forwarding doesn't work

I just had fiber internet installed today and it’s working great, except for port forwarding. I noticed that my router states the WAN IP as 100.127.x.x while using websites to check my IP returns 96.43.x.x. In my limited searching the only thing I could find similar is a post on dd-wrt where someone mentioned carrier-grade nat which if that’s the case it sounds like I’m essentially stuck behind an isp level “router” that blocks the ability to port forward.

Has anyone else come across this issue before and were you able to resolve it? Having really good upload speeds had me excited since connecting to my local network with a VPN would be much faster, but if port forwarding doesn’t work not sure if I’ll be able to do that.

Yes you are behind CGNAT. You will have to use some sort of VPN solution to easily overcome it.

100.x.x.x is CGN carrier grade NAT.
You will have to talk to your ISP for a public IP on your box,if they have that option.
If not a cheap VPS and wireguard are your friends.

Thanks for the confirmation. I hope my ISP will play nice and give me a public IP, if not I might be back for some more advice.