Please leave your NAS settings regarding SMB protocol levels on default - changing them will most likely not help you with the current issue and SMB 1 is insecure.
If you run the RoonServer App on DSM 7, then it’s simply impossible to add shares in Roon because DSM 7 doesn’t allow installed apps to mount shares - use instead the possibilities provided by the operating system (DSM 7). You can then add the local folder where you mounted the remote share in Roon (make sure to set the correct access rights).
- Main discussion thread for DSM 7 related issues: Roon Server on Synology DSM 7 Situation
- Follow-up thread: Roon on DSM 7 No Longer Beta