[GH-ISSUE #3277] [Windows 11 26H2] Built-in AmneziaWG fails with WSAEFAULT, while standalone AmneziaWG 3.1.0 works #1524

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opened 2026-10-13 20:44:14 +00:00 by bsakaguchi · 0 comments

bsakaguchi commented

2026-10-13 20:44:14 +00:00

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Originally created by @retverd on GitHub (Oct 12, 2026).
Original GitHub issue: https://github.com/amnezia-vpn/amnezia-client/issues/3277

Describe the bug

The AmneziaWG connection built into AmneziaVPN 5.0.3.0 fails on Windows 11 26H2.

The tunnel interface is created successfully, but the client cannot send or receive UDP packets. The service log repeatedly reports errors from WSASendMsg and WSARecvMsg:

wsasendmsg: The system detected an invalid pointer address in attempting to use a pointer argument in a call.

wsarecvmsg: The system detected an invalid pointer address in attempting to use a pointer argument in a call.

As a result, the AmneziaWG handshake never completes.

Environment

AmneziaVPN: 5.0.3.0
Windows: Windows 11 26H2
Windows build: 26300
Architecture: x64
Wintun: 0.14
Protocol: AmneziaWG
Standalone AmneziaWG for Windows: 3.1.0

Troubleshooting performed

I tried the following without success:

Rebooted the laptop
Disabled split tunneling
Disabled Kill Switch
Confirmed that ByeDPI and Zapret are not installed
Confirmed that DNS settings are obtained automatically through DHCP
Flushed and renewed the network configuration
Checked the Winsock catalog
Checked installed network filters
Confirmed that AdGuard and other third-party Winsock providers are not installed

The same AmneziaWG configuration works correctly:

On a mobile phone connected to the same Wi-Fi network
In standalone AmneziaWG for Windows 3.1.0 on the same laptop

This confirms that the server, configuration, Wi-Fi connection, UDP connectivity, and MTU are working correctly.

Additional observations

AmneziaVPN automatically sets the tunnel MTU to 1376. The failure occurs before the first UDP handshake packet can be sent, so changing the MTU or DNS settings does not appear relevant.

Standalone AmneziaWG 3.1.0 works correctly with exactly the same configuration on the same Windows installation.

This strongly suggests a regression or incompatibility in the AmneziaWG tunnel implementation bundled with AmneziaVPN 5.0.3.0 on Windows 11 26H2.

Workaround

I currently use standalone AmneziaWG for Windows for AWG connections. AmneziaVPN can still be used for VLESS.

Logs attached.

AmneziaVPN.essentials.log

Originally created by @retverd on GitHub (Oct 12, 2026). Original GitHub issue: https://github.com/amnezia-vpn/amnezia-client/issues/3277 **Describe the bug** The AmneziaWG connection built into AmneziaVPN 5.0.3.0 fails on Windows 11 26H2. The tunnel interface is created successfully, but the client cannot send or receive UDP packets. The service log repeatedly reports errors from `WSASendMsg` and `WSARecvMsg`: ```text wsasendmsg: The system detected an invalid pointer address in attempting to use a pointer argument in a call. wsarecvmsg: The system detected an invalid pointer address in attempting to use a pointer argument in a call. ``` As a result, the AmneziaWG handshake never completes. ## Environment - AmneziaVPN: 5.0.3.0 - Windows: Windows 11 26H2 - Windows build: 26300 - Architecture: x64 - Wintun: 0.14 - Protocol: AmneziaWG - Standalone AmneziaWG for Windows: 3.1.0 ## Troubleshooting performed I tried the following without success: - Rebooted the laptop - Disabled split tunneling - Disabled Kill Switch - Confirmed that ByeDPI and Zapret are not installed - Confirmed that DNS settings are obtained automatically through DHCP - Flushed and renewed the network configuration - Checked the Winsock catalog - Checked installed network filters - Confirmed that AdGuard and other third-party Winsock providers are not installed The same AmneziaWG configuration works correctly: - On a mobile phone connected to the same Wi-Fi network - In standalone AmneziaWG for Windows 3.1.0 on the same laptop This confirms that the server, configuration, Wi-Fi connection, UDP connectivity, and MTU are working correctly. ## Additional observations AmneziaVPN automatically sets the tunnel MTU to 1376. The failure occurs before the first UDP handshake packet can be sent, so changing the MTU or DNS settings does not appear relevant. Standalone AmneziaWG 3.1.0 works correctly with exactly the same configuration on the same Windows installation. This strongly suggests a regression or incompatibility in the AmneziaWG tunnel implementation bundled with AmneziaVPN 5.0.3.0 on Windows 11 26H2. ## Workaround I currently use standalone AmneziaWG for Windows for AWG connections. AmneziaVPN can still be used for VLESS. Logs attached. [AmneziaVPN.essentials.log](https://github.com/user-attachments/files/33356106/AmneziaVPN.essentials.log)

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amnezia-vpn/amnezia-client#1524

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