WebSocket Connection Fails to Recover After PC Sleep, Even with Manual Page Refresh

[ccccmagicboy]

Problem Description

When a PC resumes from sleep mode, the WebUI application's WebSocket connection fails to recover. This issue persists even after attempting a manual page refresh. The application displays a "WebUI Error: Connection with the backend is lost." message, and the browser itself shows a "Connection refused" error page when trying to reconnect. This indicates a fundamental breakdown in communication that is not resolved by standard recovery mechanisms.

This problem significantly impacts user experience, as it requires a full application restart to re-establish functionality.

Problem Reproduction Steps
Environment:

Operating System: Windows 11
Browser: Latest version of Edge
WebUI Version: Commit 20bfc37
Application: Text Editor in C using WebUI (as per issue.jpg)
Reproduction Steps:

Launch the WebUI application. Observe the initial connection status.
Put the PC into sleep mode (e.g., by closing the laptop lid or manually triggering sleep).
Resume the PC.
Observe the error message on the WebUI itself (similar to issue.jpg): The application window shows a red banner indicating "WebUI Error: Connection with the backend is lost."
Attempt to manually refresh the page (e.g., by clicking a refresh button or pressing F5).
Observe the browser's error page (similar to refresh.jpg): The browser displays a "Oops... unable to access this page" or "Connection refused" error, with suggestions like "Check your network connection" and "ERR_CONNECTION_REFUSED."
Expected Behavior:

After resuming from sleep and attempting a page refresh, the WebUI should detect the connection loss and attempt to re-establish the WebSocket connection.
Communication between the frontend and backend should resume normally.
Actual Behavior:

The WebUI displays a persistent "WebUI Error: Connection with the backend is lost." banner.
The browser shows a "Connection refused" error page, indicating that the attempt to reconnect to localhost is failing at the network level.
Even with manual page refresh, the connection is not restored.

I would appreciate it if any help:

Analyze the root cause of why the backend server becomes unreachable or fails to accept new connections after PC resume, even when the page is refreshed.
Provide guidance on how to ensure the WebSocket server and its network bindings are correctly managed across PC sleep/resume cycles.
If more diagnostic information is needed, please let me know.
Thank you for your time and effort in addressing this critical issue!

[AlbertShown]

Thank you for the report @ccccmagicboy, I think webui.js already designed to re-connect after connection is lost. Perhaps, the issue is the server (backend), it will close the server when PC goes to sleep.

The solution is to make server never closes, waits forever.

int main() {
    webui_set_timeout(0); // Wait forever (never timeout)

    int w = webui_new_window();
    // ...
    webui_wait();
}

[AlbertShown]

If you are using Zig:

pub fn main() !void {
    webui.setTimeout(0); // Wait forever (never timeout)

    var w = webui.newWindow();
    // ...
    webui.wait();
}

[ccccmagicboy]

Thank you for your quick response and solution, @AlbertShown !

I have added webui_set_timeout(0) to the server code as you suggested, and my initial tests show that the issue seems to be resolved. The WebSocket connection appears to recover successfully after the PC resumes from sleep, and manual page refresh not needed anymore.

However, I will conduct more extensive testing to ensure the solution is robust across different scenarios (e.g., longer sleep durations, different app and os, etc.). I will update this thread with my findings once the tests are complete.

Your explanation about ensuring the server never closes and waits forever was very helpful. Thank you for your support and for creating such a great library!

[AlbertShown]

You are very welcome @ccccmagicboy
Let me know if you find any issue