I bought a cheap UGREEN USB 3.0 Gigabit Ethernet Adapter, which is based on the ASIX AX88179 chipset. I found that it would periodically (usually while under load) stop transmitting/receiving packets, and shortly after that, its LEDs would turn off. Apparently AX88179 adapters are often flakey like this.
Cycling the Linux network interface running on top of the adapter using
ip link set dev eth0 down and
ip link set dev eth0 up didn’t get it working again. This is unfortunate since I run PPP over this ethernet link to connect to the internet. It seemed like the only fix was to reboot the machine.
However, I did find a solution to soft-reset the adapter by using the
USBDEVFS_RESET ioctl system call.