It's hard because Asus keeps renaming the setting AND moving it around... Initially it was called "Reduce USB interference" or something like that. Enabling the setting would disable USB 3.0, and cause compatibility issues.
Now, they call it "USB Mode", and it should be left on 3.0.
If that's the case, I can only say, I am (and I believe others as well) experiencing the opposite. I've seen lots of users report USB drives failing in USB 3.0 mode yet being able to mount it when switching to USB 2.0 mode.
I've tried (at least) the following USB drives over the past months in USB 3.0 mode and
they will all fail to mount:
Kingston DataTraveler 64Gb USB 3.0 (DTSE9G2/64GB
Kingston DataTraveler 16GB USB 3.0 (DTSE9G2/16GB)
Sandisk Ultra Flair 64GB USB 3.0 (SDCZ73-064G-G46)
Sandisk Extreme GO 64GB USB 3.0
Philips Circle 64GB USB 3.0 (FM64FD145B/10)
These drives
will however work in USB 2.0 mode (but consequently with lower transfer speeds).
All of these USB drives:
- were purchased new and specifically to be used on my RT-AC68U
- were partitioned on the router. Existing default partition was removed using fdisk, a new partition (type 83, Linux) was created, covering the maximum size (fdisk default for first and list block).
- were formatted on the router using mke2fs -t ext4 -L <name> /dev/sdaX and with mke2fs -t ext2 -L <name> /dev/sdaX. So no 'esoteric partition schemes' used whatsoever.
- were partitioned and formatted with Minitool Partition Wizard on Windows, by deleting the existing partition and creating one, full sized partition where both ext2 and ext4 have been tried.
- had extended filesystem checks using e2fsck when partitioned and formatted on the router.
- had full surface checks using the Verify Disk option in Minitool Partition Manager.
- fail in USB 3.0 mode and are only recognized in the USB 2.0 port or in the USB 3.0 port with USB 2.0 mode set.
- will mount without issues on my laptop using Ubuntu, Linux Mint or Debian 9
- will be recognized without issues by using Minitool Partition Wizard, on a Windows 10 laptop
Several drives were additionally partitioned and formatted using Ubuntu's Disk Utility, but I can't recall which ones. Not that it matters, but for the sake of completeness. Also, 2 or 3 of these USB drives (again, I can't exactly recall which ones) mount without issues on my previous router, a Netgear R6300v2.
Occasionally they will mount on my RT-AC68U in USB 3.0 mode, either with the preloaded partition coming straight out of their package and on some, rare occasions even with an ext2/ext4 partition, but they will almost certainly fail to mount at the next reboot, so basically unreliable to be used with Entware and other scripts.
In addition to that: I've had several occasions when having another USB drive plugged into the USB2.0 port and when I inserted one of the drives mentioned previously into the USB3.0 port, the
USB2.0 LED on the front of my router starting blinking (instead of the USB 3.0 LED) during mounting (on the rare occasions it would actually work). But most of the time, the router just doesn't see the drive inserted into the USB 3.0 port (until I disable 3.0 mode, after that, they'll all just work but at the cost of a lower speed)
So either I'm doing something wrong or there's something else going on.
