Here`s why you can`t use an NVMe (M.2) drive as storage on a Synology NAS
(Android Central)

Best answer: No. Several Synology NAS models have NVMe (M.2) slots for adding the latest SSDs, but you can only use them for caching. Synology has stated that heating issues prevent these drives from being used for storage. NVMe (M.2) drives as NAS storage: Here`s what you need to know The best Synology NAS models have slots for NVMe (M.2) SSDs, but they are limited to caching. Synology has two forms of caching — read-only and read-write — and slotting in an M.2 SSD for caching does lead to a noticeable difference in performance in select use cases. M.2 drives run too hot to be a viable medium for NAS storage — but there is an alternative. However, there`s no option to use these M.2 slots for storage, and the main reason for that has to do with overheating. During the launch event for DSM 7.0, Synology has clarified that it doesn`t allow the use of M.2 slots for storage because of heating issues. A NAS enclosure is designed to run 24/7, and even though they`re not handl...