To add AddType .html you need to :

– In Direct Admin > Custom HTTPD Configurations, click on the php config file behind the user name. (in my case php-fpm 5.6)
– In the local/user Custom 1 field (in my case php-fpm 5.6 |CUSTOM1|), enter the following:

Code:

|?LIMIT_EXTENSIONS=`LIMIT_EXTENSIONS` .htm .html|
or
|?LIMIT_EXTENSIONS=.php .php52 .php53 .php54 .php55 .php56 .php60 .php70 .php71 .inc .php56 .html|

– After saving, the security.limit_extensions value is changed in the file below it, and there should be no errors.

Custom HTTPD Configurations > click on the domain

enter the following:

<FilesMatch "\.(html)$">
    ProxyErrorOverride on
    AddHandler "proxy:unix:/usr/local/php56/sockets/admin.sock|fcgi://localhost" .html
</FilesMatch>

– replace the *username* in the handler url above with the username you have