How can I find that how many devices or which devices are connected in my LAN?

1. SoftPerfect Network Scanner

2. Advanced IP Scanner

3. LanSpy

if it is cisco router you can use show run command.

run something like Spiceworks.... it will tell separate the routers, switches, desktops, Laptops etc for you

https://www.youtube.com/watch?v=1k5mWyc_6v0

Or use scan program tool

you can use MAPI tool from Microsoft windows it is a good assets management tool intenerated with your AD

Go to

1. Run
2. Type "cmd"
3. Type "net view"

ARP is your friend.

arp -a

if you use cisco devices on network .. type the command  show cdp neighbor details 

You can display all devices connected using command prompt -> run -> cmd -> net view

Or use Scan program tools

You Can Use net view Command..

either using DHCP or login to switches and check which IPs or Mac addresses are connected to each switch