[Mashiro]

Report back if you have any luck with your findings.

Feel free to post your current vHost configuration and the used .htaccess files.

If as you say you have no redirect in your code or via htaccess or via DNS records then most likely the vHost is indeed the issue and your findings might solve the problem.

IP based vHosts are bit problematic if you have only a single IP address but multiple hostnames / domains.