I tried crafting a link by replacing the 7360 with 7530 and it was accepted.
"The FRITZ!Box supports:
USB storage devices with a maximum of four partitions,
Partitions up to 4 terabytes in size,
The file systems NTFS, FAT/FAT32 and ext2/ext3/ext4. "
Now, there's something wrong with that, because it implies GPT support. You could test GPT support with a much smaller test device, and see whether it "eats it" or not.
The limitation of four partitions is strange too, seeing as that is a Legacy MSDOS partitioning limit for primary partitions. But Legacy MSDOS can have more than four total, by using Extended/Logical for the excess.
A GPT partitioned disk has:
1) First partition of type 0xEE, sized to cover the whole disk. So the partition size declared would be 2TB (max size as far as legacy MSDOS is concerned). This is the protective partition declaration, to prevent MSDOS machines from messing around with the disk. Strictly speaking this is optional, but it's provided more or less standard when setting up a disk this [GPT] way.2) 128MB partition table storage area, not visible to all Windows utilities.
3) Once that amount of stuff is set up, then you can declare a single entry in (2) partition table area describing a 4TB partition if you want.It's just a surprise that a FritzBox would understand such a thing, as typical router-boxes-with-file-serving are only MBR partitioned and support stuff like FAT32 (because at the time, it was "free" or nearly so).
A disk doesn't have to be 4TB in size to be "prepared the GPT way". Smaller disks will work for a test. GPT disks can be prepared in Vista/W7/W8/W10. The only ugly bit, is I find sometimes when you try and remove GPT from the disk, later on utilities will insist it's still GPT when it is not. It can require a bit of "erasing work" to knock some sense into it.
Paul