Article URL: https://www.jeffgeerling.com/blog/2026/getting-25g-ethernet-mac-thunderbolt/ Comments URL: https://news.ycombinator.com/item?id=49125034 Points: 66 # Comments: 38

I've been using the built-in 10 Gigabit Ethernet on my Mac Studio for a few years. It works fine: I can edit 4K video straight off my NAS over the network, and run backups at around 1 GB/sec. But... I want more. I upgraded my rack and my NAS to 25 GbE a couple years ago, and wanted to upgrade my main workstation, too. I looked up 25G networking options for the Mac, and they're all crazy expensive: The problem is Macs all require Thunderbolt adapters; you can't just plug an inexpensive(ish) PCIe card into a Mac (RIP Mac Pro). I stopped looking until I saw this blog post. Christian Kohlschütter found a cheap 25G Thunderbolt adapter that uses a server-pulled OCP 2 NIC with a little Thunderbolt 3 adapter board. And it works on any computer with Thunderbolt. Back in January, it was only $160, which was insta-buy territory for me. Since that time, the Amazon listing jumped to $299, which still might be good compared to the Sonnet... but you might have to go digging through some Chinese sites to find a non-marked-up version now. Once I had pulled some new fiber to my desk (where I only had Cat6A cabling before), I tested the bandwidth using iperf3 between my Mac and my NAS. That's when I ran into two problems: The version of iperf3 I was running on the NAS was too old. Without multi-threading, it maxed out at 15 Gbps.