Внимательно с IP!!!!
/ip pool
add name=dhcp_pool_lan ranges=192.168.72.20-192.168.72.254
/ip dhcp-server
add address-pool=dhcp_pool_lan disabled=no interface=bridge_lan lease-time=1d10m name=dhcp_srv_lan
/ip dhcp-server network
add address=192.168.72.0/24 dns-server=8.8.8.8 gateway=192.168.72.1