That's the parameter write mode. 0 saves to EEPROM, 1 saves to RAM. If 1, a reboot reverts the drive to settings previously in EEPROM.
Another possibility, have not tried, is that ADC is enabled and the PLC controlling the drive is overwriting the parameters you're setting. One thing you can do to test this is try changing the last octet of the IP (C132) again, and before restarting the drive, view that parameter once more to see what its value is.
The C series of parameters aren't necessarily the actual value being used by the drive, for example. The F, or diagnostic group, contains what is currently being used. When you restart the drive, the C parameters you set would be written to these locations:
F693 [EN IP Addr Act 1]
F694 [EN IP Addr Act 2]
F695 [EN IP Addr Act 3]
F696 [EN IP Addr Act 4]
F697 [EN Subnet Act 1]
F698 [EN Subnet Act 2]
F699 [EN Subnet Act 3]
F700 [EN Subnet Act 4]
F701 [EN Gateway Act 1]
F702 [EN Gateway Act 2]
F703 [EN Gateway Act 3]
F704 [EN Gateway Act 4]
So again, by checking to see if the C params are overwritten after you set them, but before restarting the drive, will probably help find the cause.