I have ownCloud OR nextcloud running on my Synology DSM6 DS3175+.
In the admin configuration page the Security & setup warnings section reports:
No memory cache has been configured. To enhance your performance please configure a memcache if available.
Further information can be found in our documentation.
Please double check the installation guides , and check for any errors or warnings in the log.
How to fix:
Be sure the PHP cache option on Synology is set (Web Station => PHP Settings => Enable PHP Cache).
Edit the configuration file <owncloud_root_dir>/config/config.php adding the following line:
Cache feature will start to work immediately.