Renewing the certificates is the right thing to do, but you linked the How-To on extending the CA certificate. 
The right article is this one: Renewing the complete SSL certificate chain
Best regards
Jan-Luca
Renewing the certificates is the right thing to do, but you linked the How-To on extending the CA certificate.
The right article is this one: Renewing the complete SSL certificate chain
Best regards
Jan-Luca