how can I solve chain issues?

Chain issue is very serious problem in websites or server.

Let's figure out it.

apache(yourdomain.conf){in etc/apache2/sites-available}

-ssl example.

<VirtualHost *:443>

ServerName your domain
SSLEngine on
SSLProtocol all -SSLv2 -SSLv3 or TLSv1 TLSv1.1 TLSv1.2 TLSv1.3
SSLCertificateKeyFile yourdomain.key.pem
SSLCertificateFile yourdomain.crt.pem
SSLCertificateChainFile Chainfile of domain
SSLCACertificateFile CA certificatefile

</VirtualHost>

-segtigo limited ssl example.

<VirtualHost *:443>

ServerName your domain
SSLEngine on
SSLProtocol all -SSLv2 -SSLv3 or TLSv1 TLSv1.1 TLSv1.2 TLSv1.3
SSLCertificateKeyFile yourdomain.key.pem
SSLCertificateFile yourdomain.crt.pem
SSLCertificateChainFile USERTrust_RSA_Certification_Authority.crt
SSLCACertificateFile AAA_Certificate_Services.crt

</VirtualHost>