I am running Mac OS 10.12.2 on a brand-new MacBook Pro 15” touchbar computer. I purchase the Gigabit Ethernet adaptor to speed up Apple’s Migration Assistant between the new MacBook Pro and my old model (mid 2010 MacBook Pro 15") (also running 10.12.2), which has a built-in gigabit ethernet port. I’m using a 3ft Belkin crossover ethernet cable. I downloaded and installed the driver on the computer I’m using the Plugable ethernet adaptor with.
The issue I’m experiencing is that Migration Assistant will work fine for approximately 5 minutes at the start with throughput of approximately 70MB/s. Then it will suddenly drop the ethernet connection and switches to WiFi (excruciatingly slow). If I unplug the ethernet adaptor and re-insert it into the USB-C / Thunderbolt 3 connector it will start using the ethernet connection again for a couple of minutes and then will start having “connection lost” issues.