URLs with special characters. Error 404 not found

[drauta]

I'm migrating some websites from old server with virtualmin, some websites have files with special characters as à,ö,ç etc...
On the other server the files (images for example) are served well but on the new server with plesk 11.5 error 404 appears. (Nginx reverse proxy is activated)
Any advice?
Thank You!

 

[drauta]

I discovered that this wordpress rewrite on htaccess is making this issue:

RewriteRule ^(.*/)?files/(.*) wp-includes/ms-files.php?file=$2 [L]

Any ideas?

 

[drauta]

Please halp ;-(
I discovered on other website (drupal) that apache serves static files with special chars these way:
http://www.example.com/sites/default/files/documents/Reglament de Règim Disciplinari_0.pdf

Instead of standard utf-8 encoder url:
http://www.example.com/sites/default/files/documents/Reglament de Règim Disciplinari_0.pdf

Notice the "e%CC%80" == (e´) VS "%C3%A8" == (é)
What can I do?