Bad speed - 5gbit/s usb ethernet realtek adapter

malopaul

New Member
Apr 26, 2025
3
1
3
Hello,
I'm trying to install a realtek 5gbit/s usb ethernet adapter on proxmox because my internal NIC is limited at 1gbit/s.
I've installed the driver recommended by the vendor : r8152.

ethtool -i enx803f5dd0047e
Code:
driver: r8152
version: v2.19.2 (2024/10/21)
firmware-version:
expansion-rom-version:
bus-info: usb-0000:00:14.0-3
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: no
supports-priv-flags: no

When I'm doing a speedtest on my VM (using ubuntu) I can reach around 350mbit/s but not more. With the original NIC I was up to 800mbit/s
1746102592281.png

I've set the speed of the usb adapter from 1000 mbit/s to 5000 mbit/s but it doesn't change anything.

ethtool enx803f5dd0047e
Code:
Settings for enx803f5dd0047e:
        Supported ports: [ MII ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Full
                                2500baseT/Full
                                5000baseT/Full
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Supported FEC modes: Not reported
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Full
                                2500baseT/Full
                                5000baseT/Full
        Advertised pause frame use: No
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Link partner advertised link modes:  100baseT/Full
                                             1000baseT/Full
                                             2500baseT/Full
                                             5000baseT/Full
        Link partner advertised pause frame use: No
        Link partner advertised auto-negotiation: Yes
        Link partner advertised FEC modes: Not reported
        Speed: 5000Mb/s
        Duplex: Full
        Auto-negotiation: on
        Port: MII
        PHYAD: 32
        Transceiver: internal
        Supports Wake-on: pumbg
        Wake-on: d
        Current message level: 0x00007fff (32767)
                               drv probe link timer ifdown ifup rx_err tx_err tx_queued intr tx_done rx_status pktdata hw wol
        Link detected: yes

I have it set on OVS bridge. Set the MTU from 1500 to 9000 but again doesn't solve my problem
1746102351721.png

This is not a hardware or cable problem since I've tested it on my PC.

The iperf3 looks good.
iperf3 -c localhost
1746102935348.png

Since i'm a beginner I've been looking for 2 days on this problem, tried a lot of things and couldn't find any solution.

Do you please have any advice for my problem ?
 
That looks like USB 2 speeds. Are you sure you're connecting the adapter to a USB 3 port ?
  1. Look at the port color
    • Many USB 3.0 ports have a blue interior (though not all).
    • USB 2.0 ports are usually black or white inside.
  2. Check for labeling
    • Some ports are labeled "SS" (for SuperSpeed), which indicates USB 3.0 or higher.
    • If it says USB 3.1 or USB 3.2, that’s even faster but still backward-compatible with 3.0.
And.. I hate to state the obvious but check if your upstream connections all support and provide 5Gbit/s or more and have proper connections between them :
  • Switch
  • Router
  • ISP