A new group of USB Ethernet adapters built around Realtek’s RTL8159 controller is offering a smaller and less expensive route to 10-gigabit networking, although testing shows that host-port capabilities can sharply limit real-world performance.
Technology reviewer Jeff Geerling tested an $80 WisdPi model that connects over USB 3.2 and uses an RJ45 network port. That price was more than twice the roughly $30 cost of the 5 Gbps model in his comparison, but less than half the amount he said he had paid for 10 GbE Thunderbolt adapters. The USB device was also considerably more compact than the older Thunderbolt hardware.
The strongest result came from an AMD desktop equipped with a USB 3.2 Gen 2x2 port rated for 20 Gbps. On that system, the adapter reached about 9.5 Gbps in one direction, close to the practical ceiling of a 10-gigabit link after overhead. Upload performance on the same machine was around 5 Gbps. Other tested computers, including Macs and a Framework machine, delivered roughly 6 to 7 Gbps because their USB connections did not provide the same 20 Gbps host bandwidth.
Compatibility also varied by operating system. The Macs recognized the adapter immediately without a separate driver installation, although their network settings incorrectly displayed a 2500Base-T connection. Windows recognized the hardware but did not establish a network connection until the latest Realtek driver was installed. Geerling noted that inconsistent USB naming and limited port labeling can make it difficult for buyers to determine whether a computer supports the required Gen 2x2 mode.
The thermal result was another point of distinction. During a short bidirectional iperf3 test, the WisdPi unit reached 42.5 degrees Celsius. At a USB 2-limited speed, it drew about 0.86 watts, though the measurement method could not assess power use under full-speed operation. Geerling therefore described both the thermal and power observations as non-comprehensive. The observations cover one model and a limited group of computers, rather than every RTL8159 implementation or host configuration.
The adapter’s value depends on the network and computer around it. Owners of an existing 10 GbE network using copper RJ45 connections may benefit from the smaller format, especially if their computer provides a 20 Gbps USB port. Systems limited to 10 Gbps USB can leave much of the advertised network capacity unused. For users who do not need the highest throughput, the testing found a 5 Gbps WisdPi adapter achieved 4.6 Gbps on an M4 MacBook Air, making slower adapters the more economical option. Thunderbolt remains relevant when full 10 GbE performance or SFP+ connectivity is required.
