It turned out there were just some delays, as the Realtek USB LAN device showed up with lsusb: The first time I inserted the adapter into the USB 3.0 port of my laptop, I thought it had some issues as I could not find any new USB messages in dmesg. So that must be the footprint for external EEPROM, as for instance, 93C46 EEPROM is available in various 8-pin packages Info in Ubuntu 20.04 The description of the Realtek chips states that “The RTL8156B(S) features embedded One-Time-Programmable (OTP) memory that can replace the external EEPROM (93C46/93C56/93C66)”. The back of the XHT156B v2.0 board has an unpopulated footprint with 8 pins. The adapter is based on Realtek RTL8156B “10/100/1000M/2.5G Ethernet controller for USB 3.0 applications”, and a low-profile RJ45 jack that makes it fairly thin (for a USB Ethernet adapter). I’ve done all testing first before taking it apart, but let’s show the photos of the internals to see exactly what we have here. 2.5GbE USB dongle teardown: RTL8156B inside The dongle comes with a driver CD, but I did not use it as I connected the dongle to my laptop running Ubuntu 20.04. The package, marked “USB to LAN Gigabit Ethernet Adapter”, has “USB 3.0” and “2.5 Gbps” ticked, a good sign since it is just what I ordered… USB 3.0 to 2.5Gbps Ethernet adapter unboxing There’s some issue with Radxa E25 (it won’t boot it), so I ended up testing the dongle with UP Xtreme i11 mini PC. I purchased a no-name dongle for under $15 ( 475 THB on Lazada) in Thailand, but a USB 3.0 dongle that looks exactly the same can also be purchased on Aliexpress with either a USB Type-A port or a USB Type-C port. I intended to start testing 2.5GbE networking with UP Xtreme i11 mini PC and Radxa E25, but I thought it might be a good idea to get a USB 3.0 to 2.5Gbps Ethernet adapter just in case. Late last month, I received hardware to test 2.5GbE and WiFi 6 with namely a Radxa E25 SBC, Xiaomi AX6000 WiFi 6 router, and an 8-port TP-Link 2.5GbE switch.

Usb c to ethernet adapter speed test