Thanks for help Vova. I’ve sorted it. Synology was default setting user = admin and no password i went into synology gave it a password then put this into Roon and it connected to NAS.
Just one other question. Ive set my iphone as a remote and set roon to receive remotes. When my imac is asleep the iphone will not connect to roon!
All the processing in Roon is done by the Core. The Remote versions just control the Core. So when your iMac is asleep your Core is asleep and your iPhone has nothing to control.