openssl req -new -nodes -keyout my-app.key -out my-app.csr -newkey rsa:2048

subdomain.mywebsite.com uses an invalid security certificate.

The certificate is only valid for *.eu1.frbit.net

(Error code: ssl_error_bad_cert_domain)

Country Name (2 letter code) [AU]:GB
State or Province Name (full name) [Some-State]:London
Locality Name (eg, city) []:London
Organization Name (eg, company) [Internet Widgits Pty Ltd]:My Website
Organizational Unit Name (eg, section) []:
Common Name (e.g. server FQDN or YOUR name) []:subdomain.mywebsite.com
Email Address []:admin@mywebsite.com

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:My Website Ltd