Have you had your drive(s) for a while? Could be WDDA throwing up the warning. See this video if you haven't already https://youtu.be/jx4i64uqsIA?si=BbV1GGCL6GRJ3VM8
or this article too https://nascompares.com/answer/understanding-wdda-warning-on-wd-drives-should-you-replace-your-nas-drives/#What_is_WDDA
DS224+ will likely give you really good performance based on what you mentioned. Although the max RAM (6GB) could potentially be a concern if you run too many containers