Program for simulating subnet

Hey, i'm new to this subreddit so I don't know if this has been asked here, but is there program that would simulate your home subnet?

I would like to get clear image on what routers, computers and switches etc. are connected to my subnet and their ips. Maybe even see all the devices that are connected to wifi, since it would help with security. So is there some program that would give a clear image of what devices are there and what devices are connected to what (if that would be even possible to do). I know that for people experienced in subnetting this probably wouldn't be relevant but for newbie like me this would probably help to get a clear whole picture of the subnet. Also if there is some other easy way to for example debug your subnet in case of something doesn't work, please let me know.