Message: Could not resolve host: shop6.local
Is your host reachable under http://shop6.local? Try to use the IP-Adress instead. It could be a problem with ur Network-Config not Shopware.
However… Instead of chmod 777 you better should give the Webserver user the ownership of the directory.
For Apache2 with www-data as user:
sudo chown -R www-data:www-data /var/www/