Web API : Zoom Phone Downloads

[app.auditsystems.pro (auditsystems.prod)]

API Endpoint(s) and/or Zoom API Event(s)

get /phone/recording/download/{fileId}

Description
Our site (.net 8) attempts to download a file . This started Saturday after working for over a year. We are still able to get tokens.

Error?
System.AggregateException: One or more errors occurred. (The SSL connection could not be established, see inner exception.)
—> System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.
—> System.Security.Authentication.AuthenticationException: Authentication failed because the remote party sent a TLS alert: ‘HandshakeFailure’.
—> System.ComponentModel.Win32Exception (0x80090326): The message received was unexpected or badly formatted.

How To Reproduce

1. In C# .Net 8 app attempt to download with recording url provided from Zoom.

using (var client = new HttpClient())
{
    var request = new HttpRequestMessage(HttpMethod.Get, recordingUrl);
    request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);

    var response = client.SendAsync(request).Result;

throws the above error. We are still able to get Oauth Tokens. I can run this in different environments, but not from our production server anymore. We do currently have Tier 2 ticket for this, but wanted to explore the forum if it might helpful. I have inspected packets but I’m an amateur and only see that there is a TLS handshake error. Our Windows 2019 server has TLS1.2 and can authenticate with any other service but Zoom currently.

2. Authentication method or app type: Server-To-Server OAuth

[app.auditsystems.pro (auditsystems.prod)]

Our network admin installed IIS Crypto and used best practice settings and that fixed the issue. I suspect the cipher we agreed to use during the handshake was causing issues?

packet inspection showed we offered to use AES_128_CBC_SHA . But it fails during the handshake.