Hi @Veracious, we checked your Apache configuration and could not find anything wrong.
Keep in mind that Varnish caches all contents of requests, so if you break something it will keep like that until the cache is reloaded.
Apache is working at port 81 so it is better if you try to access Apache directly for now (e.g. http://mydomain.com:81/phpmyadmin). If not, you must restart Varnish each time you want to try a change:
sudo /opt/bitnami/ctlscript.sh restart varnish