Using rumqttc and rustls, I am trying to connect to a broker that uses a self-signed certificate, however, I get a BadSignature error.
The certificate works with another application (using other language/libraries). I’d really appreciate any help how should go ahead.

Current Behavior

Error on poll: Tls(Io(Custom { kind: InvalidData, error: InvalidCertificate(BadSignature) })

Code

let mut roots = rustls::RootCertStore::empty();
let file = File::open(cert_path).expect("There was an issue loading the ca certificate file");
let mut reader = BufReader::new(file);
let certs = rustls_pemfile::certs(&mut reader);
for cert in certs.flatten() {
        roots.add(cert).expect("Could not add ca certificate.");
}

let client_conf = ClientConfig::builder()
        .with_root_certificates(roots.clone())
        .with_no_client_auth();

mqtt_options.set_transport(Transport::tls_with_config(client_conf.into()));

let (client, mut eventloop) = AsyncClient::new(mqtt_options, 10);

loop {
        let notification = eventloop.poll().await.expect("Poll failed.");
}

Certificate

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: C = DE, ST = <ST>, L = <L>, O = <O>, OU = <OU>, CN = <CN>, emailAddress = <mail>
        Validity
            Not Before: May  3 06:39:54 2021 GMT
            Not After : May  1 06:39:54 2031 GMT
        Subject: C = DE, ST = <ST>, L = <L>, O = <O>, OU = <OU>, CN = <CN>, emailAddress = <mail>
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                        00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:
                        00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:
                        ...
                        00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:
                        00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Alternative Name: 
                DNS:localhost, DNS:develmqtt.mydomain.com, IP Address:127.0.0.1, IP Address:1.1.1.1
    Signature Algorithm: sha256WithRSAEncryption
    Signature Value:
        00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:
        00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:
        ...
        00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:
        00:00:00:00:00:00:00:00:00:00:00:00:00:00:00: