I think they're likely both correct and both wrong. It's typical for you to get one IP when behind a CGNAT but see a different IP that often rotates on sites that show you the IP your traffic is coming from.  If you are behind a CGNAT which it sounds like you'll have to play a network trick to bypass the CGNAT. Let's first try to determine for sure if this is the case.  If on Windows open a command prompt  Windows key - R for the run box.  Type cmd and hit enter. now type without