R3 Let's Encrypt Certificates causing SSL Connection Errors

We are getting errors connecting to app.ordoro.com.

The errors from dotnet are:
System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.
Inner-> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure

There certificates involved are issued by Let’s Encrypt (R3). I also noticed that AWS has a large banner message stating there are issues with EC2 because of problems with Let’s Encrypt certificates.

I found this article about problems with these certificates:

Please advise what actions we need to take or what actions Ordoro will be taking to resolve these certificate issues.

This issue was being caused because the AWS lambda container did not trust the let’s encrypt certificate. AWS has updated the lambda image and this is resolved.