Hello, I tried both and didn´t work.
I had:
# Mod_security can interfere with uploading of content such as attachments. If you
# cannot attach files, remove the "#" from the lines below.
#<IfModule mod_security.c>
# SecFilterEngine Off
# SecFilterScanPOST Off
#</IfModule>
ErrorDocument 401 default
ErrorDocument 403 default
ErrorDocument 404 default
ErrorDocument 405 default
ErrorDocument 406 default
ErrorDocument 500 default
ErrorDocument 501 default
ErrorDocument 503 default
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule .*
https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
# If you are having problems with the rewrite rules, remove the "#" from the
# line that begins "RewriteBase" below. You will also have to change the path
# of the rewrite to reflect the path to your XenForo installation.
#RewriteBase /xenforo
# This line may be needed to enable WebDAV editing with PHP as a CGI.
#RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
#RewriteEngine On
#RewriteCond %{HTTPS} off [OR]
#RewriteCond %{HTTP_HOST} !^www\.domain\.net$ [NC]
#RewriteRule ^(.*)$
https://www.domain.net/$1 [L,R=301]
RewriteEngine on
RewriteCond %{HTTP_HOST} ^domain.net [NC]
RewriteRule ^(.*)$
https://www.domain.net/$1 [L,R=301,NC]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [NC,L]
RewriteRule ^(data/|js/|styles/|install/|favicon\.ico|crossdomain\.xml|robots\.txt) - [NC,L]
RewriteRule ^.*$ index.php [NC,L]
</IfModule>
then I tried
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^domain\.net$ [NC]
RewriteRule ^(.*)$
https://www.domain.net/$1 [R=301,L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [NC,L]
RewriteRule ^(data|js|styles|install) - [NC,L]
RewriteRule ^.*$ index.php [NC,L]
</IfModule>
and I also tried what you said, both .htaccess and including the code in the index.php.
They didn´t work.