I have a commercial, small business service from COMCAST which includes I think 4 or 5 static IP addresses. I have one computer that is wired directly into the COMCAST modem and statically configured for one of the IPv4 addresses. If I do commands like "ip addr" it correctly shows the IPv4 address.

However, if I go to a public reflector like whatismyip.com, it shows my public address as being IPv6 and shows an IPv6 address.

What could be going on or how can I diagnose this further?