I have the latest iMac M4 with Tahoe and I'm taking Time Machine BackUps on my Synology DS415play.
Recently Apple announced that she would no longer support afp but only smb, so I changed everything on my NAS to SMB. Since then, Time Machine connects to my disk, but it can not take a backup returning message "Try taking a backup when diskstation.local is available". Can you help ?
The issue isn’t your setup, it’s a compatibility glitch in how Time Machine handles SMB session authentication and Bonjour discovery with some NAS devices like Synology and QNAP.
Here’s what you can try right now, remove your current Time Machine destination, then manually mount your NAS share via Finder using “smb://diskstation.local”, make sure the volume is visible on your desktop, and then re-add it in Time Machine preferences.
Also, confirm that SynologyAssistant has access in System Settings > Privacy & Security > Local Network, and your Mac and NAS names only use standard ASCII characters (no accents or symbols).
If it still fails, it’s a confirmed macOS bug. Report it via Feedback Assistant and keep your Synology firmware updated, since both Apple and Synology are working on patches for this exact problem.
That is certainly weird !!!
Suddenly I can NOT take Time Machine BackUps on my Synology NAS
