I used an old NUC with ubuntu to do this, except the backup was performed by my server rather than software on the NUC, makes it with easier that way, imo. Auto start in bios and Wireshark set to always connect.
I do recommend a wired connected if possible. So if someone messes with the wifi it won't matter.
No, I don't keep track of consumer NAS as I DIY everything. I can recommend that but I recognize it's not for everyone. I see that it's popular to use an Intel NUC or similar as the server hosting Plex and other apps, and leave the NAS simply for storage; that's very enticing.
Do not put a rack mount server in a living room, especially a 1U. The boise will never be manageable for that kind of room.
Also, the server will idle around 100 watts. The NAS much less.
Serverpartdeals
And you do not have 7TB HDDs in it. Recheck that.