> do not buy a USB-C RealTek RTL8156-equipped multi-gig ethernet dongle to use with your Mac.

Buying a Mac with built in 10gbe is so nice compared to dongle hell.

But it’s not 25gbe

I have the SABRENT USB-C to 2.5Gbps adapter as well (also bought late 2024) and can echo this sentiment. I had it connected to a M3 Pro MacBook Pro and could never get anywhere close to 2.5Gbps from it. I never found other complaints at the time either and was starting to blame poor wiring in my walls until I replaced it with Ubiquiti's 5GbE adapter (which I believe uses a Marvell controller) and that has been rock solid for me.

I've had a lot of luck with the Plugable 2.5G USB-C adapters, although on some ports they're incredibly unreliable -- I'm guessing maybe something about the power supply?

On a CalDigit TS3 dock, I've had one working off the rear Thunderbolt socket for over a year, but it fails in minutes if plugged into the USB-C one. I've never had issues with a CalDigit Elements (TB4) hub. I've had success plugging them directly into various Chromebooks. On one Windows laptop, they seemed to work on one USB-C port but not the other.

So... reliable once working, but getting there can be a pain.

Interesting! I'm using a TS3 dock and my entire use case is to bypass the 1GbE on the dock and get 2.5G to my work laptop. But once I started having issues I took both my laptops directly to my main switch to rule out house wiring issues, so I didn't spend much time dealing with the different ports on the TS3.

My logic was that I didn't want to spend $400+ on a TS4 for my WORK computer, just to get a faster ethernet for the lulz. I was happy to spend $25 for bragging rights.

Of course, now that I've spent that same $25-30 4 times, it's beginning to feel like less of a bargain.

The CalDigit TS3 dock has two different USB 3 controllers inside of it, each driving half the ports. One from Fresco Logic and one from ASMedia. I can't recall which one right now but one of them is unstable crap and the other one is better. You can see which one you're using in the Mac System Report (AppleUSBXHCIFL1100 vs AppleASMediaUSBXHCI). So try switching around ports. The Thunderbolt is a pure passthrough so that will use Apple's own USB-C controller.

These were my notes

* Front 5Gbps USB-C Fresco Logic

* Front 5Gbps USB-A Fresco Logic

* Rear 10Gbps USB-C ASMedia

* Rear USB-A, Right-hand 3 Fresco Logic

* Rear USB-A, Left-hand 1 ASMedia

Seconded - those RealTek dongles are no good.

For my Macs, the IOCrest USB4 adapters with the AQC113 chipset have been rock-solid and can saturate my 10Gbe network. They do run hot but no stability issues. That's what I use and recommend.

The newer RTL8159 based dongles are smaller, cheaper, cooler, and can do 10 Gbe on paper. But they top out at 7 Gbps on Macs, which don't implement the USBx2 spec.

But op said their RTL-8157, which is also RealTek, is good?

But only 5Gb not 10Gb

YMMV - I have three RTL8156 2.5G dongles - one in my Synology NAS, and two in different spots where I usually sit down in a chair and plug in my M1 Pro or iPhone to charge (on USB-C charger hubs) and have never had any issues where they drop out from throughput - at once point I had it running full bore overnight. They're from Cable Matters (2025) and Planex (2024). The only issues I have is sometimes they just don't show up when I connect and I have to disconnect and reconnect. That could also just be an issue with USB-C hubs.

I use several of those UGREENs and they work perfectly fine out of the box and for sustained load as well.