The “Apache is functioning normally” page is a default page. In this situation, it is indicating your Apache configuration needs to be updated to direct the pl.csdroppy.com or de.csdroppy.com hosts to the directory containing the WordPress codebase.
The Domain-based section of the Before You Create A Network docs page describes three ways of configuring Apache for subdomain-based multisite networks
- by configuring wildcard subdomains
- by configuring virtual hosts, specifying the same document root for each
- by creating addon domains or subdomains in cPanel or in a similar web hosting control panel
The Configuring Wildcard Subdomains docs go on to suggest using the Server Alias directive in your VirtualHost. In your case, this would be:
ServerAlias *.csdroppy.com