If you send a successful HTTP request to a server before receiving data from the sender, in the setup function for instance, it will work fine and you'll get a 200 code.

However, if you add a line in the onReceive() function of the receiver that sends the same HTTP request using your WiFi network (whenever you receive data from the esp32 sender using the same WiFi channel), it will always give you a -1 error code.

Here is an example where the first POST request is sent in setup(), and the two other POST requests are sent in onReceive() function, after receiving data two times :

Sender (does not appear on the image)

Receiver: 192.168.188.120
Server: 192.168.188.230

As you can see, the first POST request works fine (frames 105 to 120). Meanwhile, in the two last POST requests the receiver sends [RST, ACK] and does not proceed with sending payload, regardless of how the server is coded. Here is the code I used for receiver and sender:

You can reproduce this issue using the following files:

• receiver.cpp.txt
• sender.cpp.txt

The code tries to send a GET request to api.github.com before receiving data and every time it receives data in the callback function. Here is the result:

Note: I had to comment this line peerInfo.ifidx = ESP_IF_WIFI_STA; because it would not compile using Arduino.

I was able to connect to my network, but I can't send anything using internet.
I'm using a socket connection, but everytime I call it, I get an error...

The code is the same as the repository, except for the socket connection...
Does anybody had any problems like this?

Never used ESP-NOW before.... Is there a reason this will not work in the opposite direction? I need the sender to be the gateway, broadcasting to a number of receivers every few seconds.

I have modified the code to have the sender be gateway and the receivers pair themselves to it as peers. Both sender and receiver(s) report correct initialization and pairing (receivers) but the receivers never receive a msg. I tried a broadcast send AND specific MAC address with no difference. Happy to contribute my code if this is possible and I can get it to work.

Hey all,

I can confirm that you have to use the same WiFi-Channel for ESPNow-Sender and ESPNow-to-WiFi-Gateways. If you have multiple routers with the same SSID (e.g. in university or company) and you always want to use the best WiFi (so no hardcoded channel) you have to try to send the message on each channel until you get a success reply.

• Gateway on random channel

`

channel = 1

send = false;

while(!send){

    send = sendOnChannel(channel);

    if(send){

         break;

    }else{

        channel = channel % 13 + 1;

     }

}

`

The following line of code seems to not be working anymore:
peerInfo.ifidx = ESP_IF_WIFI_STA;

I get the following error

In file included from sketch\ESP_NOW_2.ino.cpp:1:0:
C:\Users\..\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.7\cores\esp32/Arduino.h:194:12: error: 'std::round' has not been declared
 using std::round;
            ^
C:\Users\..\..\Documents\Arduino\..\ESP_NOW_2\ESP_NOW_2.ino: In function 'void initEspNow()':
ESP_NOW_2:139:20: error: cannot convert 'esp_interface_t' to 'wifi_interface_t' in assignment
   peerInfo.ifidx   = ESP_IF_WIFI_STA;
                    ^
Multiple libraries were found for "WiFi.h"
 Used: C:\Users\..\..\..\Arduino15\packages\esp32\hardware\esp32\2.0.7\libraries\WiFi
 Not used: D:\Program Files\Arduino\libraries\WiFi
exit status 1
cannot convert 'esp_interface_t' to 'wifi_interface_t' in assignment