@tadori8
You can use a USB ethernet adapter with the new Roku Express 3960, but not previous models due to the hardware limitations of the previous models.
The supported devices and models along with known compatible USB adapters can be found on this Support page. https://support.roku.com/article/360058027813
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102