Please note that switching the used PHP version in Strato's admin panel will overwrite your .htaccess. You need to manually read the rules from .htaccess.dist after changing the PHP engine.
1&1 let you change the used PHP version to PHP5 per directory by adding
AddType x-mapp-php5 .php AddHandler x-mapp-php5 .php
to your .htaccess
Alternatively you can also change the PHP version at the control center of 1&1.
When the Strato ServerSide security option is enabled, some file uploads as well as some dokuwiki page edits may fail. When editing a page you sometimes get an error message: “Service temporarily unavailable.” if the page containes strange words. On file uploads the upload ends with a “Failed” status if a PDF unusual things. The ServerSide security option can be disabled in the Strato server administration web interface.