Experiencing persistent error 3101 when attempting to log into FFXI. Message pops up after I hit accept to the terms. This is happening with a completely clean setup and I have exhausted all standard troubleshooting steps.

I've fully uninstalled and reinstalled Final Fantasy XI and PlayOnline Viewer multiple times,
manually deleted all leftover folders (Program Files + Documents PlayOnline),
installed to a clean directory (C:\FFXI), and tested on a brand new local Windows user profile.

On the network troubleshooting side, I've disabled IPv6, reset Winsock and IP stack (netsh winsock reset, netsh int ip reset), flushed DNS, tested on alternate network (mobile hotspot), I can confirm no VPN or proxy usage, I've rebooted my router, I also use a wired connection.

On the security/firewall/anti-virus side I fully disabled Windows Firewall for testing, added exceptions for PlayOnline and FFXI executables, and I uninstalled my antivirus.

On the basic system side, I've confirmed that system date/time is correct, confirmed Microsoft Edge WebView2 present, enabled TLS 1.0/1.1/1.2 in Internet Options, ran PlayOnline as administrator, tested compatibility modes in Properties, and disabled DPI Scaling.

I'm at a loss here and really want to get back onto my account. Please help me.