Is there such thing as a gigabit USB 2.0 Ethernet adapter? There is, but they’re hard to find because gigabit runs faster than the limits of USB 2.0. But you can use a gigabit USB 3.0 Ethernet adapter on a USB 2.0 port and it will function.
When you plug a USB 3.0 Ethernet adapter into a USB 2.0 port, it will still work at reduced speed, as long as your operating system has a driver for it. It will still negotiate a gigabit link speed with your Ethernet switch, and you’ll get whatever speeds your system can manage. It will be faster than 100 megabits.
Gigabit on a USB 2.0-equipped laptop
From time to time I use a Realtek-based gigabit USB 3.0 adapter on an old Dell laptop that only has USB 2.0 ports. I have software on that computer that I can’t transfer to another one and it creates large files, so it’s nice to be able to move those files around a little faster when I need to.
When I plugged the adapter in, Windows 10 installed the driver without any issues. I connected the adapter to my gigabit switch using a CAT5e cable, and the two synced up at 1 gigabit. If your adapter or switch only have activity lights, and no lights to indicate the link speed, you can still check your speed. To check link speed, right-click on the network adapter icon in the lower half of your screen, then click Open Network & Internet Settings, then click Network and Sharing Center, then, finally, click Ethernet.
If yours doesn’t sync at a gigabit, try a different cable. Sometimes cables go bad, and if you’re like me, old CAT5 cables sometimes get mixed up with good CAT5e cables.
I then ran a speed test. The theoretical limit of USB 2.0 would be around 480 megabits. In my testing, I was able to get around 250-300 megabits out of it. Your results will vary, but you’re likely to get better than 100 megabits, and gigabit USB adapters don’t cost much more than 100-megabit adapters now. If you don’t care about chipsets, you can get a gigabit USB adapter on Ebay for around $10. And if you’re willing to pay around a dollar extra, you can even get one with a built-in USB hub. An older USB 2.0 100-megabit adapter costs around $6. So you can get double your speed for less than double your money, which is nice.
What to do when your USB adapter doesn’t work
If your USB gigabit adapter doesn’t work, it’s probably a driver issue. Even though USB itself is backwards compatible, the system you use the newer adapter on has to support the hardware inside.
Recent versions of Windows should have drivers for all of the common network chipsets, so you can use all kinds of weird combinations of hardware and expect it to work. Other operating systems may vary.
If you’re planning to use a gigabit USB adapter with an older Mac or a game console, I recommend you double check what network chipsets your device supports, then make sure you buy a USB adapter with that chipset in it. In the case of a Mac, you may have to load a driver, but as long as a driver exists, it should work.
Why you can’t use a USB 3.0 gigabit adapter in a Wii or Wii U
The Wii and Wii U is a perfect example of this. The ASIX AX88179 chipset that’s compatible with the Nintendo Switch isn’t compatible with a Wii or Wii U because those systems don’t have drivers for the newer chipset, they only support the older ASIX AX88772 100-megabit chipset.
You may have to pay a slight premium to get a device that specifies an exact chipset, especially to get an ASIX chipset compatible with Nintendo game consoles. Don’t assume that an unmarked adapter that looks exactly the same has the same chipset inside.
Is USB to Ethernet fast?
USB to Ethernet can be faster than wireless, depending on the wireless standard. But USB imposes overhead, so a USB-connected Ethernet adapter probably won’t run as fast as Ethernet connected straight to your motherboard.
So it really depends on your definition of fast. On a device that doesn’t have built-in Ethernet, a wired Ethernet connection is probably going to be faster than wireless at least some of the time.
The computer I use for work doesn’t have built-in Ethernet, so I use a Realtek-based gigabit USB to Ethernet product with it. I routinely push data around at faster than 900 megabits with it. That’s pretty fast.
What does backward compatible with USB 2.0 mean?
When a product states it’s backward compatible with USB 2.0, that means it’s designed for USB 3.0 but USB 2.0 will work. If you’re talking about a computer with USB 3.0 ports, that means USB 2.0 devices work in them. If you’re talking about a product designed to plug into a USB 3.0 port, it means it works when you plug it into a USB 2.0 port. It will just be slower.
The caveat with backward compatibility is that you also need a driver.
Can a USB 2.0 be used in a USB 3.0 port?
A USB 2.0 device is electrically compatible with USB 3.0. So as long as the device has a driver for it, you can use it. For example, you can use a Wii or Wii U USB 2.0 Ethernet adapter in a Nintendo Switch. But I have a USB 2.0 Ethernet adapter sitting on my desk that won’t work on either device, because Nintendo game consoles don’t have a driver for the chip in that adapter.
But I’ve used that adapter in my work computer’s USB 3.0 port. I also have a USB 2.0 wireless mouse and a USB 2.0 keyboard plugged into it.