There are 2 options:
1) if you created the subdomain as website:
Dont mix * and IP address in the site settings. Either use * in all sites or select the IP address in all sites but dont mix it.
2) If you created the subdomain as "subdomain" record of the site test1.mydomain.com, then it shall show the conetnt of the main site as thats the purpose of the subdomain function.