I had a similar issue aside from I never used a VPN. I downloaded the game along with multiple friends of mine to play together and not a single one of us all different locations. ISPs all running private home networks… And absolutely no assistance
The only way to find out you are IP banned is to contact support jump through all of their hoops for them to give you no help and no reason for the ban in the first place… no ability to remove the ban and nothing other than oh well wait 14 days