Thanks for the additional information. This "config.php" is how Edge Client obtains information from BIG-IP about the versions and logon modes of the APM VPN concentrator. This behavior of following the hostname but not the path part of a URL has also happened in another situation in a different version of the client. This issue might be related to security changes that have been made in the client about how links are processed / validated.
Can you open a support case and reference ID 1032505? We'll need to get the product engineering team to take a look.