title: Curl says SSL certificate is expired when it is not
body: <p>When using curl on my server to access my other servers, I get this response:</p>
  <pre><code>curl: (60) SSL certificate problem: certificate has expired
  More details here: https://curl.haxx.se/docs/sslcerts.html
  
  curl performs SSL certificate verification by default, using a &quot;bundle&quot;
   of Certificate Authority (CA) public keys (CA certs). If the default
   bundle file isn't adequate, you can specify an alternate file
   using the --cacert option.
  If this HTTPS server uses a certificate signed by a CA represented in
   the bundle, the certificate verification probably failed due to a
   problem with the certificate (it might be expired, or the name might
   not match the domain name in the URL).
  If you'd like to turn off curl's verification of the certificate, use
   the -k (or --insecure) option.
  </code></pre>
  <p>Using curl from my local machine or opening the same URL in the browser displays the certificate as valid. The problem seems to be due to <a href="https://letsencrypt.org/2021/10/01/cert-chaining-help.html" rel="nofollow noreferrer">letsencrypt shutting down support for an older root certificate</a>. But I am just not able to update the trusted root certificates of the server. <br />
  I tried <code>update-ca-certificates -f -v</code> and manually downloading the updated root certificates via <code>wget https://curl.se/ca/cacert.pem -O /etc/ssl/certs/cacert.pem</code> but nothing works.
  Any ideas?</p>