Secure HTTPS request fails 90% of the time

Question

I'm using a NodeMCU, which is connected to an enterprise network at a school. The information given in the GET requests that the ESP8266 sends is sensitive, so naturally we want to make it secure and encrypted - enter SSL. We do the request like so;

HTTPClient http.begin(url, thumbprint)

However, on the network at the school, doing this request fails 90% of the time, so I did a few tests - 100 requests to the exact same IP and certificate, noting how many went through;

• School network
  • HTTPS requests: 10/100 successful [10%]
  • HTTP requests: 100/100 successful [100%]
• Private home network
  • HTTPS requests: 100/100 successful [100%]
  • HTTP requests: 100/100 successful [100%]

We have also tried using the WiFiClient class, and while 100% of the requests went through, each one took 15 seconds which is too long.

My question is; what would the problem be, and what can we do to fix it? Can I do something in the code, or on the network?

Answer 1

Increase the timeout for your request with HTTPClient.setTimeout(). Note the timeout is in milliseconds.

HTTPClient http;
http.setTimeout(15000); // 15 Seconds
http.begin(url, thumbprint);