Persistent Connection Failure No903: Tried All Standard Fixes (Worked Yesterday, Broken Today)

H

HallowedAutistic

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Hi everyone,

I'm completely stuck trying to resolve a sudden Connection Failure No903 (failed to connect to patch server) error on my Ultima client. The game was working perfectly fine yesterday, but today it refuses to connect. I know the server is online and active, but my client won't pass the patch stage. I've already gone through extensive troubleshooting to isolate the issue, and none of the following methods have worked:
  • Antivirus & Folder Exclusions: The entire Ultima directory is explicitly excluded in Windows Defender. There are no quarantined files, and the main game screen does NOT show a "DLL Error."
  • Windows Firewall: Both psobb.exe and psobbw.exe are completely allowed through the firewall for both Private and Public networks.
  • Launcher Configurations: "Test Server" is completely disabled in the launcher options, and the launcher is set to "Run as Administrator."
  • Directory Path: Moved the entire Ultima folder out of Program Files and placed it directly into the root drive directory (C:\) to completely bypass Windows UAC restrictions.
  • Network & DNS: Flushed my DNS cache (ipconfig /flushdns) and entirely disabled IPv6 on my network adapter properties to force a clean IPv4 connection.
  • VPN / Hotspot Test: Tested the client using a mobile phone hotspot connection and a separate VPN network to see if it was an ISP routing issue. The 903 error persists on both.
  • OS Compatibility & Registry: Toggled compatibility mode for Windows XP (Service Packs 2 and 3) on the executables, and completely cleared out the HKEY_CURRENT_USER\Software\Sonic\Phantasy Star Online Blue Burst registry tree to force a clean config reset.
Since it worked yesterday and my system environment hasn't changed, I am completely out of ideas. Does anyone know if a recent background Windows update or server-side network change might be causing this loop specifically for the patch server handshake?

Any advanced help or insight would be greatly appreciated. Thanks!

 
You mention Ultima in your post, you're aware these are the forums for an entirely different server, right?
 
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