Magento 2 permission fixes - server skills required

Hello After moving my website to new hosting company I had some permission issue on the new server, I thought permissions issues were solved. We run command to test cron job if it works or not and seem to causes permission to return. Would like to solve permission issues once and for all, I found this info in the logs: I have HIDDEN the domain in the log [login to view URL]: [2019-03-15 03:52:18] [login to view URL]: Warning: file_put_contents(/var/www/HIDDEN/data/var/cache//mage-tags/mage---01b_MAGE): failed to open stream: Permission denied in /var/www/HIDDEN/data/vendor/colinmollenhour/cache-backend-file/[login to view URL] on line 663 {"exception":"[object] (Exception(code: 0): Warning: file_put_contents(/var/www/HIDDEN/data/var/cache//mage-tags/mage---01b_MAGE): failed to open stream: Permission denied in /var/www/ HIDDEN /data/vendor/colinmollenhour/cache-backend-file/[login to view URL] on line 663 at /var/www/HIDDEN/data/vendor/magento/framework/App/[login to view URL])"} [] [2019-03-07 17:45:36] [login to view URL]: Class Magento\Indexer\Model\Indexer\StateFactory does not exist Class Magento\Indexer\Model\Indexer\Interceptor generation error: The requested class did not generate properly, because the 'generated' directory permission is read-only. If --- after running the 'bin/magento setup:di:compile' CLI command when the 'generated' directory permission is set to write --- the requested class did not generate properly, then you must add the generated class object to the signature of the related construct method, only. {"exception":"[object] (RuntimeException(code: 0): Class Magento\\Indexer\\Model\\Indexer\\StateFactory does not exist [login to view URL]: [2019-03-15 07:25:14] [login to view URL]: Warning: file_put_contents(/var/www/HIDDEN/data/var/cache//mage-tags/mage---01b_MAGE): failed to open stream: Permission denied in /var/www/HIDDEN/data/vendor/colinmollenhour/cache-backend-file/[login to view URL] on line 663 [] [] [login to view URL]: [Mon Mar 11 10:32:41.671363 2019] [core:error] [pid 17409] (13)Permission denied: [client [login to view URL]] AH00132: file permissions deny server access: /var/www/HIDDEN/data/pub/static/adminhtml/Magento/backend/en_US/[login to view URL] [Mon Mar 11 10:32:42.097284 2019] [core:error] [pid 17211] (13)Permission denied: [client [login to view URL]] AH00132: file permissions deny server access: /var/www/HIDDEN/data/pub/static/frontend/Infortis/ultimo/da_DK/[login to view URL], referer: https://HIDDEN/pub/static/version1552296663/adminhtml/Magento/backend/en_US/[login to view URL] [Mon Mar 11 10:32:45.037929 2019] [core:error] [pid 17409] (13)Permission denied: [client [login to view URL]] AH00132: file permissions deny server access: /var/www/HIDDEN/data/pub/static/adminhtml/Magento/backend/en_US/[login to view URL]