MS Teams plugin and Let's Encrypt certificates

Hello all,

My colleagues have developed an MS Teams plugin which connects to a Web server via the https protocol.
We had some problems when trying to test the plugin with a self signed certificate on the web server side.
The communication wasn't possible at all.

The problem was solved after we changed the self signed certificate with one from a trusted CA.

Currently i am testing the plugin with the Let's Encrypt certificate and the results i got are really strange.

The communication between the plugin and the Web server is fine when using the:

• MS Teams Web client
• MS Teams Windows desktop client
• MS Teams IOS client

But there is a problem when testing it with the MS Teams Android client.

I have tested it with Android versions 11 and 12 but the result is always the same, there is no communication with the Web server.

The question is if the Let's Encrypt certificates are supported by Microsoft for the MSTeams plugins.
If not can you please provide a link with the supported CA?
Thanks in advance,