USB 3.0 interferes with wifi something bad. Can you force USB 2.0 mode somewhere in the menus? One idea might be to get a powered USB 2.0 hub to put between the router and the external HDD, forcing it to use USB 2.0 mode.
Correct. A few manufacturers have shielded ports, which can help. Most with USB3 ports have an option in the admin page to downgrade the USB3 port to USB2.
Not sure why router manufacturers ship routers with USB3 ports at all. At the very least shield them!
This can also be an issue connecting a USB3 device to a laptop, but generally the Wifi antennas are far enough from the location of the actual ports (9 times out of 10, they are in the display section) that the interferance is minimal and/or unnoticable. Not so much when your port is probably located a couple of inches from your antennas.
It can cause whicked bad problems when using something like a Wifi USB adapter or Bluetooth USB adapter when right next to a port using a USB3 device.
You'd think it would be one of the things the USB Alliance realized when designing the USB3 specification (IE they are transmitting in roughly the 2.4GHz band over the wire!!!).
Something I pray is fixed with USB3.1, that they move to something away from Wifi, like 4GHz or something.