If you’ve ever tried using Time Machine with a NAS pre-APFS days you’ll know the experience left a lot to be desired. I was encouraged by a colleague to give this another shot and am happy to report a huge improvement in speed and performance.
The initial backup of my machine, which was roughly 80GB of data took about 70 minutes to complete. I am also happy to report that Time Machine remembers the location of the NAS and will auto-mount it as needed.
If you’re using an UnRAID NAS, you will find this guide helpful:
https://wiki.unraid.net/UnRAID_6/Configuring_Apple_Time_Machine