your isp is sharing an IP with other customers? i have never, ever seen that in 3 countries worth of residential isps and doubt its possible and want to make sure its true (and concerning)
If you have ever used mobile data, you've shared your IP address with other customers. Many residential ISPs around the world also use CGNAT. I had to call the customer support of mine to have a dedicated IP address. Other providers may force customers to pay for a static IP address if they want to avoid CGNAT.
The ISP I am using does have NAT, but I was able to disable the NAT using the modem setting. (When they replaced the modem, I told them what setting I changed and they were able to put that setting into the new modem too) It is a dynamic address, but I can accept incoming connections and the IP address rarely changes (although it has happened before).
Having your own address in most places is a part of a "dedicated business line". My ISP in Switzerland literally refuses to issue so called "static" addresses at all, business or not.
you'll see it called CGNAT (aka Carrier Grade NAT) and it can be a really big annoyance for a lot of things, usually I see it on mobile/cell connections but I've heard of some DSL providers here in the states using it too.
