Excellent Big Sur compatibility, but concerned about future support

macOS Big Sur appears to be using a Driver Extensions (DEXTs) to provide support to most USB network adapters built with Realtek chipsets. This allows for simple plug-and-play compatibility. But my testing has shown than CPU usage is excessive with the Apple provided DEXT. It interferes with normal system operation. For example, it causes stutters in system audio. Furthermore, on gigabit or faster connections, the DEXT is unable to reach actual gigabit speeds, instead reaching actual performance that typically tops out between 600 and 700 Mbps.

I noticed this behaviour first when I purchased an OWC Thunderbolt Dock. But the performance issue is present in most USB network adapters with Realtek chipsets that I’m aware of.

The performance was unacceptable so I searched for a workaround and found this Plugable adapter. The Plugable adapter’s performance is top-notch, reaching full gigabit speeds on my Internet connection. Furthermore, CPU usage is a fraction of the other network adapters that I’ve tried.

When I dug into why this may be the case, I noticed that the Plugable adapter – while still totally plug & play – does NOT use the problematic DEXT. Instead, it seems to use a regular kernel extension.

As kernel extensions are on the way out, I’m wondering if Plugable is aware of the performance issues with the standard driver extension? I’m worried that future versions of macOS will deprecate the KEXT that the Plugable adapter relies on, resulting in the same problematic behaviour.

That said, for the time being, those Big Sur users observing sub-standard performance from your other Realtek-based network adapters can rest assured that the USBC-E2500 is a trusty workaround. It will work reliably and perform as expected.

Hello Paul,

We have been in contact with Realtek regarding drivers for macOS Big Sur (and above).

While the performance of the adapter is good with the ncm driver provided within macOS, there are a number of smaller issues that occur with that driver. Such as incorrect packet count reports in macOS, incorrect link rate reports within various Terminal tools and network device settings UI, etc.

We are looking to provide a better experience here, but I don’t have additional information that can really be shared publicly at this time.

In short, we’re aware of some benefits and issues here, and we’re doing what we can to make things better for a variety of Realtek network adapters.

Plugable Technologies

Thanks so much, this is is precisely why I picked up the Plugable adapter. I had picked up another Plugable device a couple of years ago and was impressed with the level of support you provided there. After reading the very thorough analysis your company did of the ASIX network chipset drivers shipping on Big Sur, I figured that the USBC-E2500 which you recommended specifically for Big Sur would be well-supported. It’s been a great experience so far.

While I’m not concerned about the minor issues with the NCM driver you’ve just brought to my attention, I appreciate that you’re monitoring the situation and it would be great if you could maintain a support document so we can track the state of these Realtek/Apple drivers, particularly during major operating system upgrades. As I’ve worked through this Realtek networking issue, I have realized many other vendors seem to be completely bypassing any level of involvement in the shipping drivers for their hardware, to the point of being completely unfamiliar with the driver performance. It’s rather unfortunate.

Many of these problems are rather ‘in the weeds’ as far as issues go. As mentioned in my last post, there’s not a lot to share publicly here if we were to maintain a dedicated support document on progress. Likely, once ready, we’ll provide a release driver via our driver page and update the documentation surrounding the USBC-E2500. Alternatively, these fixes may be included in a macOS update, but this is purely speculation and not indicative of what will actually be present in an upcoming macOS update.

It is also likely when a driver is available, we’ll note it in our blog similar to what was done with the ASIX adapters. There is an atom feed on our blog that you can subscribe to, or you can sign up via email to get notified of updates in our blog using the form at the footer of our website.

I hope this helps. Thanks for all the positive feedback, and continued use of our products!

Plugable Technologies

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