May I ask what kind of IoT device are you running? Is it ESP32 or? Maybe some PLC like S7-1200? 
Over which port? 443 as HTTPS?
Does the IoT device has itself certificate already or you’ve added it via code?
Are you using any library(ies) for such case?
Using Atmel?
Without it, does it work okay?
Hi fritex,
Thanks for reading my post. I had trouble quoting your post so I will just answer your questions here.
My system is based on the Microchip SAMW25 xPlained Pro hardware and the ASF library. (So yes, since Microchip bought Atmel years ago to get their ARM solutions, it is Atmel. 
)
Yes, port 443.
I load the certificates through an API. Debugging at the WiFi module level within the SAMW25 indicates that SSL with TLS 1.2 is encrypting/decrypting just fine.
It works great with curl, but only on a Linux machine since the API key has characters that Windows doesn’t like.
Here is the curl command that works:
GET /api/live/flight-positions/full?bounds=50.682%2C46.218%2C14.422%2C22.243 HTTP/1.1
Host: fr24api.flightradar24.com
User-Agent: curl/7.81.0
Accept: application/json
Accept-Version: v1
Authorization: Bearer (private key deleted)
Thanks again.
Dave