What do you mean by "registered".
Domain Name System (DNS) has no impact on IP addresses be they static or dynamic. It is simply an index that converts from domain names to IP addresses. The only time this is a problem is when you're using a domain name and the ISP doesn't have "reverse DNS" set up that verfies that your IP is associated with your domain. Since there's no domain name involved, DNS isn't either.
If Netflix thought it was a VPN IP address, they would have said so.
According to Neflix's own ISP speed index (
https://ispspeedindex.netflix.com/country/us/ ), Centurylink is tied with Frontier for first place among DSL providers so it doesn't seem logical that they're blocking Netflix. By the same token, because Centurylink's operations are broken up into regions, what's happening in one area may be decidedly different from what's going on somewhere else in terms of performance. The policies should be the same across the board.
I agree that only Centurylink is going to be able to give you an authoritative answer.