Much like the Amazon Fire TV Stick 2 before it, the new Amazon Fire TV 3 supports external peripherals through a USB OTG cable. This means that, despite not having any external ports, you can still connect things like USB drives, keyboards, mice, game controllers, ethernet adapters, and more.
The Fire TV 3 has USB OTG support enabled by default. This means that you can connect external USB devices without needing to root the Fire TV, like you had to do for the 1st generation Fire TV Stick. USB OTG is enabled because the Fire TV needs OTG in order to use the official Amazon Ethernet Adapter. That same adapter is also compatible with the 2nd generation Fire TV Stick, which explains why Amazon also left OTG enabled on that device as well.
In order to connect external USB devices to the Fire TV 3, all you need is a compatible USB OTG “Y” cable that has a male micro USB plug, a female micro USB port, and a female full-sized USB A port. I know this generic OTG cable from Amazon works with both the Fire TV 3 and Fire TV Stick 2. To use it, connect the male micro USB plug on the OTG cable to the Fire TV 3, connect your external USB device to the female USB A port, and connect the Fire TV 3’s micro USB power cable to the female micro USB port on the OTG cable. With just the OTG cable, you can connect one USB device at a time, but if you connect a USB Hub to the OTG cable, you can connect multiple USB devices at once and use the simultaneously.
USB peripherals, including keyboards, mice, and game controllers, can be connected using an OTG cable. The USB receiver that comes with the Logitech K400 keyboard and touchpad, which is my personal favorite Fire TV keyboard, also works perfectly. The Fire TV 3 accepts multiple peripherals using a USB hub just fine without needing to configure any settings. Just plug them in and they work. The FLIRC IR adapter also works, which lets you control your Fire TV using any IR remote.
Using an OTG cable, you can also connect an external ethernet adapter. If you’re thinking it’s silly to connect both an OTG cable and an ethernet adapter when you can just use the official Amazon Ethernet Adapter, you’re right. If all you want to do is add an Ethernet connection, you’re better of just getting the official Amazon Ethernet Adapter. However, since the Amazon Ethernet Adapter is itself an OTG device, you cannot daisy chain an OTG cable to the official Amazon Ethernet Adapter in order to connect additional USB devices. If you want to connect an ethernet adapter and other USB devices, you’re going to need an OTG cable, a USB hub, and a 3rd-party ethernet adapter. I know this Monoprice Ethernet Adapter works perfectly with both the Fire TV 3 and the Fire TV Stick 2.
Where things, unfortunately, get complicated is with external USB storage, like a flash drive or hard drive. External USB storage does work with the Fire TV 3 when connected through an OTG cable, but there are some caveats. First off, you can only connect one external USB drive at a time, but you shouldn’t be surprised by that since that’s how all Fire TV models work with USB drives. Using a USB hub, it’s perfectly fine to connect one external USB drive and additional USB devices simultaneously. I connected a USB hub to an OTG cable on the Fire TV 3 and then connected the Monoprice Ethernet Adapter, the Logitech K400 keyboard receiver, and a flash drive to the USB hub simultaneously without any issues or configuration. They all worked perfectly.
The main issue with external USB storage connected to the Fire TV 3 via an OTG cable is that Fire OS 6 on the Fire TV 3 does not automatically mount the USB drive. This means that apps which do not have their own drive mounting procedure built in cannot directly view the USB drive. Kodi is such an app, so you cannot connect a USB drive to the Fire TV 3 and view its contents directly from Kodi or add a directory on the USB drive as a video source in Kodi.
In order to access files on an external USB drive that is connected via an OTG cable, you need to use a file manager that is capable of mounting USB drives. ES File Explorer is such an app. With a USB drive connected via an OTG cable, you can launch ES File Explorer on the Fire TV and it will immediately mount the USB drive and make it accessible. You can then browse the USB drive’s files within ES File Explorer and select to open them using other apps, such as Kodi.
Total Commander is also another app that can access external USB drives, as long as you sideload this plugin. Just like with ES File Explorer, you can browse the drive’s contents within Total Commander but not through other Fire TV apps. When you select to open a file, you’ll then have the option to use a different app to open the file. So if connecting a drive full of videos and watching them through Kodi is your goal, you can do that, but it’s obviously not as ideal as adding the drive as a video source within Kodi.
It’s worth noting that the Amazon Fire TV Stick 2 does not have this same limitation. If you connect an external USB drive to the Fire TV Stick 2 using an OTG cable, the Stick will automatically mount the drive and make it accessible to any app. This means you can browse the USB drive’s contents from within apps like Kodi as if the files were stored internally. I don’t know why Amazon decided to impose this limitation on the Fire TV 3 when it’s not limited on the Fire TV Stick 2, but I expect it has something to do with Fire OS 6. With any luck, a future Fire TV 3 software update will change the behavior and mount USB drives automatically, like all other Fire TV and Fire TV Stick devices do.
Just like all Fire TV and Fire TV Stick models except the Fire TV 1, you cannot use external USB drives to store apps on the Fire TV 3. This means that there is no way to expand the device’s internal storage for apps.
Overall, for a device that has no ports, the Fire TV is actually quite versatile, thanks to its OTG capabilities. Just be sure you’re not hanging the weight of external USB devices from the Fire TV 3’s built-in HDMI cable. I suggest placing the Fire TV on a flat surface and connecting it to an HDMI cable using a female-to-female HDMI adapter if you plan to use an OTG cable.
USB devices I’ve personally tested and known work with OTG on the Fire TV 3 and Fire TV Stick 2:
Generic USB OTG Cable
Monoprice USB Ethernet Adapter
AmazonBasics 4-Port USB Hub
FLIRC USB IR Remote Receiver
Logitech K400 Wireless Keyboard with Touchpad