AirPort Extreme 802.11ac do not show hard drive in APFS

Please remember that the AirPort Extreme 802.11ac was designed in the 2012 timeframe, long before Apple began to use APFS around 2019-2020, so the firmware for the USB port on any of the AirPort routers will only support hard drives that have been formatted in Mac OS Extended (Journaled) or FAT 16/32.

In addition, please remember that Apple discontinued the AirPort line in 2018.

If you want to use Time Machine to back up to a drive connected to the USB port on any of the AirPorts, you will need to use the Mac OS Extended (Journaled) format on the drive.

You can back up a Mac running Monterey or Big Sur (APFS formats) using Time Machine to a hard drive at the USB port of the AirPort Extreme, but the format of the backup file will be Mac OS Extended (Journaled), not APFS.

Not sure if you were aware that the USB port on the AirPort Extreme (and Time Capsule) is an old and slow USB 2.0 design, so backups are going be very slow.

This makes things more complicated, with more chances for errors to occur in the backup process. In other words, the data on your Mac will be using the APFS format, but the Time Machine backups will use the Mac OS Extended (Journaled) format.

If you had a Time Capsule, the internal hard drive cannot be formatted in APFS, so Time Machine backups to a Time Capsule will use the Mac OS Extended (Journaled) format as well for Macs running Monterey or Big Sur.

Tesserax is correct. Although the drive attached to the USB port on the AirPort Extreme will be formatted for Mac OS Extended (Journaled), the actual backup file itself will be formatted in APFS automatically by Time Machine.

So, you will have a backup file in one format on a hard drive in another format. Not exactly the most reliable way to back up, so I would not consider using this as my primary backup plan.

taddesse wrote:

Is my assumption right, that running Time Machine back-up from Monetary would not work/not advised on a HD formatted in Mac OS Extended

Time Machine will continue to work, under macOS Monterey, to create backups to drives formatted in MacOS Extended (and attached to the AirPort Extreme). When running the first backup, the sparsebundle created on that drive will actually be in APFS format. However, the drive, itself, will remain formatted in MacOS Extended.

This would be by far the best option in terms of speed and reliability for your backups. It won't hurt to also backup to the drive at the AirPort Extreme if you have a spare drive. Time Machine will alternate backing up to each drive automatically.