I got it to work... I changed the .htaccess to

RewriteEngine On RewriteCond %{HTTP_HOST} ^forum.example.com RewriteRule ^(.*)$ http://localhost:61111/$1 [NC,P,L]

and the config.json to

{ "url": "http://forum.example.com", "port": "61111", "secret": "###", "database": "redis", "redis": { "host": "/home/###/.redis/sock", "password": "", "database": "0" } }