Maybe you are IP banned?
Maybe you are IP banned?
The only way to tell is to try your luck with a different IP address to see if you can get past authentication. The Neopets team made the entire process deliberately mysterious, but if you can't log in and you can't sign up, then you're definitely IP banned. As for why you would receive one form of ban instead of the other - that could be for any number of reasons. If you're able to visit the user lookups of your accounts from another account, then don't look a gift horse in the mouth! Change your IP address and lay low on your accounts for a while.
If the Neopets team had any reason to suspect that the IPs you were using are part of a proxy or VPN pool of IPs, then they'd likely go after them. They targeted IP pools late last year, and earlier this year as well, but they received considerable backlash for outright freezing players. It turns out that plenty of folks were just using proxies and VPNs to protect themselves and not to cheat, so perhaps now they're trying out a light-touch approach to handling situations like yours. That's just a theory though.
They could be experimenting with tracking cookies or local storage in order to block you out. We know that they tinkered with that earlier this year with StackPath, which resulted in a blocks that were easily circumvented. Just to rule it out - you're definitely clearing out your browser's cookies and local storage along with toggling IPs, right?
Bowsette (12-19-2020)
If this was the case wouldnt I not be able to log in to ANY of the accounts associated with the banned IPs? Like 2/5 accounts im locked out of completely and the other three I cant create accounts but I can log into no problem. I clear my cookies when changing IPs, but with the accounts in question its a fucking miracle TNT didnt just chain freeze them all if they knew they were associated. I dont play a whole lot anymore so I guess Ill lay low for a bit and come back with a different set of IPs.