The RedNet 4, RedNet MP8R, RedNet X2P and Red 4Pre/8Pre/8Line/16Line all switch phantom power off by default when the device is rebooted.
With the X2P and Red Range if you wish to retain your phantom power settings then you can do so by enabling the 48V Retain option for those devices by entering the Tools menu for that device from RedNet Control.
The 48V Retain option can also be enabled on Red 4Pre/8Pre/8Line/16Line from the Global menu on the front panel.