Review on 2.5G Ethernet to USB Adapter, CableCreation USB 3.0 Gigabit LAN Dongle, Wired Network to USB Converter, Latest RJ45 to USB Adapter for MacBook Windows 10,8.1, macOS X 10.6-10.15, Black by Chris Wagner

First I tested this on OS X Mojave, Catalina and Big Sur on 3 different machines and the results were the same on all 3. You MUST install the latest drivers from the Realtek website to get 2.5Gbe speeds, otherwise it will only work as a regular gigabit ethernet connection (and poor quality). To reiterate, if you don't install drivers, OS X's built-in drivers only work as a gigabit ethernet port. You can verify that it's installed correctly by going to the Apple menu, selecting About This Mac, and then clicking the System Report button. In the window that opens, click on "Network" on the left. You should then see a "USB 10/100/1G/2.5G" section on the top right corner. Click on that and in the window below, filled with lots of jargon, there's a section called "Ethernet - Media Subtype". This section should say "2500Base-T". If you see 1000Base-T, you installed the drivers incorrectly and are not getting 2.5Gbe speeds. So I disabled my onboard ethernet and only tested with this USB dongle. The key overheats for 15 seconds after transferring data at 2.5Gbps, then slows down to sub-gigabit speeds. It uses 5ft Cat 6a cables, which should be well above the specs required for 2.5Gbe. Testing between PCs with a dedicated 2.5Gbps PCIe card, a single 62GB file took 10 minutes over my MacPro's built-in gigabit connection, but nearly 20 minutes with a 2.5Gbps -Connection. (Both machines also used SSDs). Looking at the traffic on my Qnap 2.5Gbps switch, I could see a burst of transmission on startup that was close to the correct 2.5Gbps, but then quickly fell below due to the adapter overheating the normal gigabit fell. This happened with another 2.5Gbe USB dongle (also based on Realtek) that I bought at the same time. Based on the reviews I knew overheating would be an issue but I didn't think it would be that bad. The CableCreations connector is larger than the other one I bought so I was hoping it would cool better, but unfortunately it doesn't. I also bought some small Revain radiators. I'll take the key apart and see if applying a proper baud rate heatsink helps. The moral of the story is that while they "work," they just aren't that good. They're good for fast data packets, but if you need 2.5Gbe, you probably play a lot and they're BAD at it due to overheating. I think I'll break down and just buy a Thunderbolt 10Gbe adapter.