This morning I tried an experiment, connecting my MacBook Pro to my Xfinity XB7 Gateway with a 2.5 gigabit LAN dongle. But I only got 1 gigabit speeds.
What was wrong?? I looked at the Plugable product description on Amazon and it said it would need drivers on Mac. So I went to their download site and saw this:
It said it basically didn’t have drivers for any release of macOS post the update to 11 when the M1 Silicon macs came out in 2020 and they were working on it with Realtek. But that was over 3 years ago.
I was mad. So I checked the Realtek site. They hadn’t updated the drivers since macOS 10.15 in 2020.
Yet, as I was looking for an updated driver or just an idea of what product would actually work, people were saying they were getting the proper speeds with products with RTL8156 chipsets. I tried a couple of port changes as one person suggested. No difference.
What was I getting wrong?
Spoiler: It really wasn’t the Realtek 8156B drivers at all
Then it occurred to me: “Does my XFinity Gateway even support 2.5 Gbps?” So I googled that.
Turns out it did, but only one out of four ports (identified by a colored stripe) supports that speed. The rest are 1 Gbps. I checked, and sure enough, I had the cable plugged into one of the 1 Gbps ports. I plugged it into the port with the stripe.
Lo and behold, it worked. Here are the results of the test I did after that.
So, while it seemed like the Realtek 8156 B chipset was the culprit, it was actually that my choice of router port on the gateway was the problem. I emphasize my choice being the problem, since the port I plugged it into was performing to specification, rather than it being the router’s fault. If you have an XFinity gateway and want the max speed out of it on your LAN, plug the LAN into port 4 (like mine) or a port with the stripe next to it.