SSL/TLS handshake failure during installation on Windows

[o08558588-cmd]

Package

Stable Diffusion WebUI Forge - Classic (Installer)

When did the issue occur?

Installing the Package

What GPU / hardware type are you using?

NVIDIA GeForce GTX 1660 SUPER

What happened?

Summary

Stability Matrix fails during prerequisite download (Python installation step) with an SSL/TLS error.
The issue is reproducible even on a fresh Windows install and on multiple PCs.

Environment

• OS: Windows 10 Pro 22H2 (x64)
• Fresh clean install
• Antivirus: Windows Defender only
• No system-wide VPN

Steps to Reproduce

1. Launch StabilityMatrix.exe
2. Start installation
3. Installation fails during Python/prerequisite download

What I Already Tried

• Reproduced on 2 different PCs
• Different networks (home + mobile hotspot)
• Defender exclusions
• Portable mode ON / OFF
• Default install path
• TLS 1.2 manually enabled (registry)
• certutil / sfc / dism
• Full clean reinstall of Windows (Home → Pro)

Question

Does Stability Matrix require a specific TLS version, cipher suite, or certificate chain?
Is there a way to enable verbose network logging?

Console output

Unpacking resources
Unpacking resources
Error: System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.
---> System.IO.IOException: Unable to read data from the transport connection: Удаленный хост принудительно разорвал существующее подключение..
---> System.Net.Sockets.SocketException (10054): Удаленный хост принудительно разорвал существующее подключение.
at System.Net.Security.SslStream.EnsureFullTlsFrameAsync…
at StabilityMatrix.Core.Services.DownloadService.DownloadToFileAsync(...)
at StabilityMatrix.Avalonia.Helpers.WindowsPrerequisiteHelper.InstallPythonIfNecessary(...)

Version

v2.15.5 (Windows x64)

What Operating System are you using?

Windows

[o08558588-cmd]

Additional details:

The issue reproduces consistently:

• On two different PCs
• On different networks (including mobile hotspot)
• After full Windows reinstall (clean install, formatted system drive)
• Windows 10 Pro 22H2 x64
• Windows Defender only (no third-party antivirus)
• TLS 1.2 explicitly enabled in registry
• System fully updated via Windows Update

The error always occurs during prerequisite installation (Python download phase).

The exception is:
System.Net.Http.HttpRequestException → SSL connection could not be established
Inner: SocketException (10054) – remote host forcibly closed the connection

Since this persists across machines and fresh OS installs, it does not appear to be caused by local corruption or firewall configuration.

Questions:

1. Is Stability Matrix using a specific TLS version or cipher suite that might be rejected?
2. Is there an offline prerequisite bundle available?
3. Can the Python download URL be provided so I can test it manually?

Ready to provide additional logs or test a debug build if needed.

Thank you for your help.