You forgot to ask:
4. Are you using a static or a dynamic (DHCP) IP setup?
5. What is your box model?
Do you remember if when using the D-Link firmware the box IP was a static one and the same that now insists on reappearing after a reboot?
If that is true, it is possible that Alt-F is reading and using a D-Link flash-stored file with that static IP value(*). That file can be removed from flash memory by using "FormatFlashSettings"; you should afterwards use "SaveSettings" to save the current in-use settings.
In any case, doing "FormatFlashSettings" followed by "SaveSettings" does no harm and is worth trying.
(*) so new users migrating from D-Link will have the same static IP they are used to.