Because if there isnt any adapter connected at that moment it will always load localhost.
First while you are on your LAN change ip to 192.0.0.128 and then start tftp, after that disconnect your lan and connect to device
But you can remain on that address, you dont really need 192.0.0.128 anyway. Once you stop bootloader on putty/securecrt you can just do set ipaddr 127.0.0.2