Yes, you can use the My Cloud EX2 Ultra as network storage for both Mac and PC and set up backups for both devices at the same time.

- Network storage: The My Cloud EX2 Ultra offers centralised network storage that allows you to store and share files, photos, documents and other data from both Mac and PC. It supports both Windows and macOS and allows data to be accessed from anywhere.

- Time Machine for Mac: You can configure the My Cloud EX2 Ultra as a destination for Time Machine backups of your Mac. This allows you to store regular backups of your Mac on the NAS.

- Backup for PC: For PCs, you can use various backup options offered by the My Cloud EX2 Ultra. For example, you can use the NAS's built-in backup tool or third-party software to perform regular backups of your PC data.

Overall, the My Cloud EX2 Ultra is well suited to serve as a centralised backup and storage solution for both platforms.