Edit/Add new IP reservations

Use router as DHCP server means that when any device on the network broadcasts a DHCP request, the router will answer it.  If the feature is off, then the router ignores DHCP requests.  (Some users deliberately set up another device to manage IP addresses on the network and disable their WiFi router DHCP to prevent conflicts.)

When the router receives a DHCP request, it goes through a process to determine how to respond.  My analysis is that it does this:

• Looks in the router ARP table to see if a device with that MAC address is already on the network.  If so, the router says "Use this IP address I found in my ARP table."
  (this is the part that we humans find annoying and wish the router would not do this.)
• If not, the router looks in the LAN Setup table for that MAC address.  If an entry is found, it responds, "Use this IP address I found in my LAN Setup table"
• If the MAC address is not in the LAN Setup table, the router looks for an open entry in the DHCP "pool" and says, "Use this IP address that appears to be available from the pool."
  (I do not know if the router starts by looking from the bottom of the table or if it starts from the last IP address that was handed out.  Would be something to experiment with (if I cared).