I posted awhile ago with the same sort of problem, That being i have an Asustor AS-U2.5G2 USB adaptor that when i connect it to my Dell XPS running manjaro and my Surface Laptop Go running Pop OS! the speeds when im copying files to my laptops are just garbage on my Dell i get about 60MBps and bout 25MBps on my Surface. I was asked to run ethtool to check to see what link spend it was connecting at so below i have provided the info.
Settings for enx00e04c68050d:
Supported ports: [ ]
Supported link modes: Not reported
Supported pause frame use: No
Supports auto-negotiation: No
Supported FEC modes: Not reported
Advertised link modes: Not reported
Advertised pause frame use: No
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Port: Twisted Pair
netlink error: Operation not permitted
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes
My server im pulling files from and uploading to is a Truenas Core system with dual Intel 10gig nics, the switch im connecting to is 10/5/2.5/1gig port.
On Windows 10 using my Dell i can get 280+ MBps but not even close on Manjaro or Pop OS!.
It says it uses the RTL8156B controller so could it just be the driver is shit on Linux?
I also have a different 1gig usb ethernet adaptor and get basically the same speeds as the 2.5gig adaptor on Linux but was able to get 113mbps on Windows 10.
Anyone have any ideas or could offer some help?