.NET MAUI Android: HttpClient POST requests are delayed/slow with multiple rapid requests (iOS works fine)

Question

I'm building a .NET MAUI app that communicates with a local server by sending HTTP POST commands. I have a class in a .NET library, and I use HttpClient to send requests. It works perfectly and instantly on iOS, but on Android, sending multiple POST requests in quick succession results in a noticeable delay:

The first command is fast

Subsequent commands take 5+ seconds each

If I wait 5 seconds between commands, each command is again fast

This is my simplified sending function (called with await each time):

internal async Task<bool> SendCommandAsync(string action)
   {
    try
    {
        var requestUri = $"https://{ip}:8080/api/command?action={action}";
        var request = new HttpRequestMessage(HttpMethod.Post, requestUri);
        request.Headers.Add("x-api-key", "xxx");
        request.Headers.Add("x-client-token", token);

        HttpResponseMessage response = await client.SendAsync(request);

        if (response.IsSuccessStatusCode)
        {
            Console.WriteLine($"Command '{action}' sent successfully.");
            return true;
        }
        else
        {
            Console.WriteLine($"Error send command: {response.StatusCode} - {await response.Content.ReadAsStringAsync()}");
            return false;
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Exception: {ex.Message}");
        return false;
    }
}

What I've tried:

Reusing a single HttpClient instance
Injecting different handlers (HttpClientHandler, AndroidMessageHandler)
Forcing HTTP/1.1 (request.Version = new Version(1, 1);)
Disabling proxies
Adding detailed timing logs (delay is always inside the await client.SendAsync(request))
Same server/network: On iOS, works as expected; on Android, delayed after first request

Additional info:

The Android app and server are on the same WiFi network
No exceptions are thrown, only delays
Not reusing any HttpContent/StringContent objects
Not using fire-and-forget; always awaiting the requests

Questions:

Why does this only happen on Android?
Is there an Android-specific setting, handler, or best practice for MAUI that fixes slow/queued POST requests?
Are there other debugging tips or known issues in .NET MAUI for Android networking I should check?

Any help or ideas appreciated!

It sounds like you're describing a throttling behavior. It's not that request takes 5 seconds, its that each request is being blocked for 5 seconds. It is as, you said, the actual request is quick. If you have some control of the end-point, you could reengineer the end point to accept a multiple inputs and provide multiple outputs, or you could spread your queries over multiple alternate end-points. — Stephen Quan
– Stephen Quan, Commented Jun 30 at 22:25
Of all the approaches you've mentioned, "Reusing a single HttpClient instance" is the only detail you should need. Perhaps something is being held on to? Is the code that calls SendCommandAsync running on UI thread? If so, I bet you've blocked UI thread while holding (something). What objects is that calling code holding on to? As an experiment, write a very simple app. (Or find an existing simple app that does work.) Put all your code into a background thread (Task.Run(...) the method that starts your sequence of HTTP requests. Stripped down to its essence, should work. — ToolmakerSteve
– ToolmakerSteve, Commented Jul 5 at 0:19
It is essential to understand that using async/await does not magically absolve you of the need to be careful about long-running methods. It is possible that somewhere on your call stack, there is a problem. Either holding on to something that causes Android to not relinquish some resource, or blocking the UI thread for "too long". This is why it is best to do a clean test "from scratch", that does the minimum required to investigate HTTP behavior. Create a minimal "working" solution. Gradually enhance that towards what you need. When you hit a wall, you'll have a good question to ask. — ToolmakerSteve
– ToolmakerSteve, Commented Jul 5 at 0:25
... If you encounter this 5 second delay even with a tiny app, then you'll have a minimal example that you can post as the question. In that case, linking to the code as a public github repo is useful. Try to include a bit more code in your question. But I'm wagering the problem won't be in the code snippet posted in question; it'll be in how you got there. That's what I mean by "somewhere in the call stack". — ToolmakerSteve
– ToolmakerSteve, Commented Jul 5 at 0:32

Matan Yamin · Accepted Answer · 2025-07-10 19:15:32Z

1

I found the solution!

The problem is with the default HttpClientHandler on Android—it causes 5+ second delays between rapid HTTPS requests to local servers, due to the way it manages sockets and connection pooling.

The fix:
Use SocketsHttpHandler instead of HttpClientHandler on Android. This handler avoids the delay and gives you instant responses, just like on iOS.

Example:

        var handler = new SocketsHttpHandler
        {
            SslOptions = { RemoteCertificateValidationCallback = (sender, cert, chain, errors) => true },
            PooledConnectionLifetime = TimeSpan.FromMinutes(10),
            PooledConnectionIdleTimeout = TimeSpan.FromMinutes(2),
            MaxConnectionsPerServer = 8
        };

        return new HttpClient(handler);

answered Jul 10 at 19:15

Matan Yamin

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