The first thing that you need to figure out is what sort of RAID your server is using. Synology RAID is functionally Linux LVM and the disk set from a Synology box can be attached to a Linux PC and repaired. But you say the RAID is on a server, and that could be a lot of different things. If the RAID was configured with RAID Host Bus Adapter, you're probably going to need to use another system with the same RAID hardware and import the RAID config. If the array was built using Storage Spaces, just having all the drives connected to a Windows Server is probably enough for the system to see the array unless two or more of the drives have been dropped.
There are specialized tools that can determine the configuration of disks in an array that won't mount. I've used Runtime Software's RAID Reconstructor in the past, albeit mostly out of curiosity since I did have a backup to restore from. I lost an array config of 12 or 14TB and had to figure out the interleave order of the drives before the array could be made to operate again, then use the application to write the data out to another volume of similar size. This process took around a month to complete but recovered around 98% of the data that had been present vs. what was in my backup.
I have never needed to do this for mission critical data. I make backups. RAID is not a backup. RAID is a tool to increase data availability.