Teardowns I've Worked On
so how is being shredded not tamper evident?
As Kirstysteve said, and such limit would likely be 2T , and since Apple ship this device with 3T is is implausible that such a limit exists.
Especially since Airport utility correctly reports the space.
If your objective if just to swap the disk, it is not necessary to remove all four connectors from the main board (which may be fiddly to reconnect). Remove just the large connector on the left (easy to reconnect) and the metal plate.
Then wiggle the rubber boot free. The SATA connector can now be unplugged from the disk (keep the disk pushed down) and the other two wires are just long enough to allow the disk to be extracted with care.
If you fit anything other than ST2000DM001, ST3000DM001, ST4000DM000 series of drives, then you may need to adjust (with a knife) the two rubber buffers at the far end (i.e. the top) of the disk slot. These are tailored to mate with a rebate in the end of the disk enclosure which is NOT universal .
This would be easy enough to do, so long as you're willing to fully extract the guts from the case. Alternatively you could always machine a 1/2 inch rebate into your preferred drive.
The ones offered are the ones that the IP standard reserves for the private class A, B and C blocks respectively.
Any other address you pick is potentially dangerous, e.g. it could be someone else's static IP address or some other public reserved space.
If you have static IP addresses, then you probably don't want to be using DHCP to dish them out.
It really wouldn't make sense since Apple aren't overcharging for the disk.
The 2G is $50 more than the Airport Extreme. Knock off your $20 for the kit and you've got $30 left to buy your 2G drive. And invalidate your warranty.
The only reason that I did this is because I needed the 4T drive. Not to be skinflint.