net/ntopng plugin certificate configuration fails to pull full certchain

[wangmaster]

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Describe the bug The ntopng certificate configuration fails to pull in the full cert chain into /usr/local/share/ntopng/httpdocs/ssl/ntopng-cert.pem

To Reproduce Steps to reproduce the behavior:

1. Go to 'Services-Ntopg`
2. Configure an ACME issued LetsEncrypt Certificate
3. Connect to https://:3443
4. depending on your client, you may get a cert error because the LetsEncrypt intermediate cert is not usually in the trust store.
5. Check /usr/local/share/ntopng/httpdocs/ssl/ntopng-cert.pem and you will see it only has a single -----BEGIN CERTIFICATE----- -----END CERTIFICATE----- block. It should have at least two. one for the cert and one for the intermediate

Expected behavior Should not see an error, or the ntopng-cert.pem file should be complete.

Additional context See https://www.ntop.org/ntopng/securing-ntopng-with-ssl-and-lets-encrypt/ step 5 which shows that the fullchain.pem (not just the cert.pem) needs to be installed properly for ntopng.

Environment Software version used and hardware type if relevant. e.g.:

OPNsense 25.1.6_4 (amd64).