As soon as you enter the LUCI interface of openwrt, you are presented with a bunch of DHCP leases corresponding to all the machines that got their IP from DHCP, but what about the computers that have static IPs ?
The answer to that is that there is no place where all this data is stored on the router, and you must scan for all machines
a tool to help you do that is arp-scan, just go into packages and install it, or simply run the command “opkg install arp-scan” from the ssh session, right after, you should be able to run the command as follows
arp-scan –interface br-lan –localnet
but this will not necessarily be the correct command, you will need to find the name of your LAN interface which is simple from interfaces in LUCI
As of now, the current version of arp-scan has a bug, where it displays the following error
arp-scan -I br-lan -l
Interface: br-lan, datalink type: EN10MB (Ethernet)
WARNING: Cannot open MAC/Vendor file /usr/share/arp-scan/ieee-oui.txt: No such file or directory
WARNING: Cannot open MAC/Vendor file /usr/share/arp-scan/ieee-iab.txt: No such file or directory
WARNING: Cannot open MAC/Vendor file /usr/share/arp-scan/mac-vendor.txt: No such file or directory
Starting arp-scan 1.9.5 with 256 hosts (https://github.com/royhills/arp-scan)
15 packets received by filter, 0 packets dropped by kernel
Ending arp-scan 1.9.5: 256 hosts scanned in 1.852 seconds (138.23 hosts/sec). 0 responded
The solution to that is by manually installing the newer arp-scan package