MY first Synology was a DS213 years ago to replace a Buffalo TERRASTATION that experienced a mobo failure. The DS213 was fine as a NAS to store my photos and files. As a single user I could easily move from my desktop to my laptop and seamlessly access my files. WIN
I bough a DS415+ to use as a "light" file server for multiple user who were all in the same physical location. Think small business with one office location. This worked well too. Conflict resolution was useful to sort out multiple people editing the same files at the same time. WIN
I then bought a RS815+ to serve as the "headquarter NAS" and moved the DS415+ to a satellite office. This is when the problems started. I setup the headquarter "master" RS815+ with CloudStation Sever and the remote office "slave" DS415+ with CloudStation Share Sync. In theory --- this should allow multiple users at both physical sites to have access to the same files. Given the multi-terabyte volume size, DropBox-like services were not cost effective nor practical. This system works - sometimes. However, periodically and without any seeming explanation, the synchronization fails and updates to one NAS are not reflected in the other. There seems to be no pattern. The only solution is to use the ADMIN acount to disable and then re-enable the shared-folder <--> Local Sync Folder two-way sharing. This then initiated a re-synchronization. FAIL
I've attempted for over a year to get technical support from Synology. So far we have not been able to fix the problem. FAIL
Compounding the problem is that Synology does not have a robust set of diagnostic tools to perform a folder-to-folder comparison. Sure, I can use a PC and FolderMatch, but this should be able to be done NAS-to-NAS directly. Further, the tools for detail folder permission and access control are too simplistic. At the minimum it would be minimum for the ADMIN to be able to switch to a user access via DSM so the the ADMIN can inspect what the user can see and access, for security confirmation. FAIL
In summary - Synology is a great upgrade to a USB hard drive attached to a single computer or router for use in a single location with a small number of users. beyond that, the sales and marketing OVERSELLS it as a replacement for a small-medium enterprise file sever. And, if you need enterprise-level tech support, you'd be better off hiring a private IT consultant. FAIL
So, why did I buy yet another Synology product. This time I needed a good solution for a single-location with small user base. This is clearly the sweet-spot for Synology, which is not yet ready for prime-time in any application more advanced.
2021/08/23 UPDATE -- My DS718+ that I purchased in January 2019 experienced a volume crash. This is unbelievable. I purchased a NAS so that my data was safe. I purchased IronWolf drives because they were integrated with Synology DSM. Synology customer support is SLOW, and then they respond with broken English and copy/paste from the other useless information. Their solution was to backup to an external USB drive, remove, and reconfigure the volume. So now I need to purchase a 7TB USB drive so I can backup my Synology. And Synology can't guarantee that I did not loose any files.
This company is a joke as so is the customer service. BE WARNED that Synology may be ok if you have a single location and nothing stored is mission critical. But they fall way short of what is promised in terms of reliability and performance.