There's a few comments here that are really far of the reason.
Internal IP address has absolutely nothing to do with this, nothing!
I can set my internal Ip address to anything I want within my subnet, I can have it auto by DHCP, or manual.
Why use that to ban??
It is PSN account bans as far as I can see (from my experience)
Running from original disc, I can not log in or start the game on my cfw psn account.
created a new user, new PSN account, I can log in and play. (same IP address internal and external, no messing with DNS,. no proxy or VPN)
I understand lots of people are experiencing different issues, some have got the same as me, but then find themselves banned again, some OFW users are experiencing the same issues.
I have read how the server is so buggy, or something in the coding in the game, that the auto banning feature is playing havok and banning lots of people in error.
Most of what I have read is second guessing I'm sure, or educated guesses perhaps.
As long as OFW users are experiencing the same issues, those on CFW will never be able to work out there issues at the same time, simply because we dont know if its related to firmware or not yet.
I will add, the player matching, finding players etc is useless currently, sitting in the lobby's for ages, so there is without a doubt server issues. (it has also just froze in the lobby)