MKR1000 SSL Certificate Tool Can't Retrieve Telegram's Certificate

I'm using Arduino MKR1000 model B.
I upload the WiFiSSLClient example for the WiFi101 library, it sends an https GET request to google successfully.
I change the sketch to make it make the GET request to, and client.connect method returns false.

The MKR1000 is able to send an http GET request to telegram, but it's not useful. The request has to be in https.

I added the following domains to the certificate upload tool:

I got the same issue when I removed from the domain list in the certificate upload tool. After seeing that, I concluded that the certificate upload tool fails to retrieve the certificate for telegram.

The same board had a sketch on it that was able to send the request to telegram in https. I wanted to add features today, so I created a sketch from scratch with the latest versions of everything, and now I'm having this issue.

To test this, make a GET request to When you make the request on your browser, you'll receive a small JSON. You should be able to get the same JSON on the MKR1000.

1 Like

Any idea how to fix this? Without the certificate, no communication with telegram bots is possible.
best, Andreas