I have gotten several DSM 7.0 memory issue notifications, sent report to Synology, and got the following E-mail:
Dear customer,
Thank you for contacting Synology support.
The Plex DLNA Serve made this problem. Please kindly stop the Plex to avoid this problem.
2021-01-09T17:20:29-06:00 NAS kernel: [344119.816825] Out of memory: Kill process 7570 (Plex DLNA Serve) score 721 or sacrifice child
2021-01-09T17:20:29-06:00 NAS kernel: [344119.826325] Killed process 7570 (Plex DLNA Serve) total-vm:21946664kB, anon-rss:10390244kB, file-rss:0kB
You also could contact Plex support for this problem.
Hope this helps and please let us know if any further assistance.
Yours Sincerely,
Martin Chou
Technical support
Synology Inc.
Let me know if there is anything you need for logs, etc.