My own approach to this problem would be to look for a new dongle with a good reputation for throughput to eliminate the dongle as the bottleneck.Product description Startech USB 3 Dual Port Gigabit Ethernet Adapter You can research this online for your OS/dongle combination. It is also possible that changes to the system’s parameters for the TCP/IP stack could make improvements. Depending on the driver, there may be options to tune the parameters used by the driver to run the dongle. One more place you might be able to improve things is in the driver configuration. If you choose to buy a new dongle, check reviews for good throughput, they are not all created equal. You can check for updates for the soft parts of this, and, of course you can replace the hardware in this case.

Similarly, it could be the implementation of the dongle hardware, firmware, or driver. You can check for firmware updates, and that might just help, but of course you can‘t do anything about the hardware. Even though the standard can support the higher rate, the hardware or firmware for the port could be limiting throughput. It could be the implementation of the USB port. The standard for USB 2.0 provides up to 280mbps, far more than you need for this application. To add a different version of mostly the same answer as others have given:

Usb 2 vs usb 3 ethernet adapter