Given that this was my pet subject for several years as elucidated in previous threads, I can state the following:
- MS O/Ss do not (or at least in the early 2000s *did* not) follow the RFC as regards lease times for DHCP.
- Many consumer router DHCP daemons do not lease the same address to the same client
If you want the same address giving to the same client, your best bet is by static allocation over DHCP - this is where you get the MAC address of your device's network card (the address is 6 pairs of hex characters separated by colons and looks akin to this: 09
7:56:b3:2a:cf), and you insert it into the router in a static DHCP allocation table against the IP address you wish to receive. That way, when your device requests an IP address it is always given the one associated to that device.
HTH
