I am using the Docker image lscr dot io/linuxserver/nextcloud along with SWAG and duckdns
when I go to https mysubdomain dot duckdns dot org/nextcloud I am getting “Access through untrusted domain”
Access through untrusted domain
Please contact your administrator. If you are an administrator, edit the "trusted_domains" setting in config/config.php like the example in config.sample.php.
Further information how to configure this can be found in the documentation.
Nextcloud – a safe home for all your data
I’ve also tried modifying the /config/config.php file, but I don’t have one.
It’s amazing what reading will do for you As a side note, barring reading the actual documentation, you can also use find to find where files are. For future reference, something like find <path to config> -type f -name "config.php" would’ve done the trick for you.