Too long DHCP discovery

[ntqbit]

Hello!

I use the latest esp-wifi revision (5578266) att the moment. I run the examples dhcp.rs and embassy_dhcp.rs for ESP32 (ESP32-WROOM-32 DevkitC board).

Most of the times DHCP discovery takes more than 9 seconds, sometimes even up to 30 seconds. Sometimes, however, it takes no time and the MCU immediately gets static IP.
But that happens rarely, about 1 in 10 times. In other times I have to wait ~10 seconds.

Although, the wifi connection and transmission/reception speed is ok (at least for MQTT), no significant delays.
Wifi connection takes almost no time, at most a few seconds.

I used two access points to connect: my home wifi and an access point created by my laptop.
With both of them I observe the same problem. The laptop and therefore the access point are located less than a meter away from the ESP32, so I think the signal quality should be great.

I measured the time it takes for the MCU to send the DHCP discovery packet with wireshark:

(192.168.12.1 is the DHCP server, the IP of the laptop's interface, 192.168.12.84 is the leased IP for the

I see that both the discovery and request packets are sent twice. Is that expected behavior?

I need to clarify that the first DHCP discovery packet is usually delayed for ~10 seconds AFTER I see the Wait to get an ip address debug line (source), for both embassy async and blocking versions.

The commands I use to run the examples:

SSID="ssid" PASSWORD="passwd" cargo run --release --example dhcp --features "wifi"
SSID="ssid" PASSWORD="passwd" cargo run --release --example embassy_dhcp --features "wifi async embassy-net embedded-svc"

Do you know what could be the problem?

Thanks!

[bugadani]

embassy-rs/embassy#2104

[ntqbit]

embassy-rs/embassy#2104

Thank you. That helped.
Indeed, following the pull request, resetting the DHCP socket after STA is connected solves the problem and DHCP discovery happens almost immediately.
However, I found that I also need to add a little delay of about 200 ms before resetting the socket. Otherwise, the problem stays.

So the code working for me (blocking version):

....
    println!("{:?}", controller.is_connected());

    let wait_end = current_millis() + 200;
    while current_millis() < wait_end {}
    wifi_stack.reset();

    // wait for getting an ip address
    println!("Wait to get an ip address");
....