Windows has one habit which I detest and I don't know why it acts this way: if you leave your drive disconnected for long enough, it will disable File History entirely and nag you about reconnecting and re-setting it up all over again. That recalcitrance is what discourages me from keeping it going at all. I just give up, it's not important enough to keep going through all that.
If it were really important for Windows not to have the drive disconnected for too long, it would issue pre-emptive warnings before the timeout was reached, but it doesn't, it just shames you after the horse has left the barn.
File history in Windows is based on shadow copies (Snapshots) that run from the server at a scheduled point. The explorer client just accesses those snapshots.
Like TM you need an external or network drive to use it. Unlike TM it's not very intuitive and Microsoft doesn't do much to advertise it.