Qualcomm Atheros AR8132网卡在Ubuntu 20.04.5 LTS下仅能达到100Mbit/s链路速度的问题求助

Hey there, let's figure out why your Qualcomm Atheros AR8132 is stuck at 100Mbit/s on Ubuntu 20.04.5 LTS. I’ve dealt with similar network speed hiccups before, so here are some practical steps to try:

• First, confirm the current link status
  Run ip link show to find your network interface name (it’ll look something like enp0s25). Then use ethtool <your-interface-name> to check the current speed and negotiation mode. If the output shows Speed: 100Mb/s, we know the negotiation is failing to reach gigabit.

• Force gigabit negotiation manually
  Try setting the interface to gigabit full-duplex mode with this command:

  sudo ethtool -s <your-interface-name> speed 1000 duplex full autoneg on
  

  After running it, recheck with ethtool <your-interface-name> to see if the speed jumps to 1000Mb/s. If the network drops temporarily, don’t panic—just revert with sudo ethtool -s <your-interface-name> autoneg on if needed, but since your Windows laptop works with the same setup, this should work.

• Check and update the driver
  The AR8132 uses the alx kernel driver on Ubuntu. Verify it’s loaded with:

  lspci -k | grep -A 3 Ethernet
  

  Look for Kernel driver in use: alx—if that’s there, the driver is active. Older kernels might have bugs with this card, so updating to the latest HWE (Hardware Enablement) kernel could help:

  sudo apt update && sudo apt install --install-recommends linux-generic-hwe-20.04
  

  Reboot your system after the update and test the speed again.

• Verify router port settings
  Even if your router supports gigabit, double-check the specific port your backup PC is connected to. Log into your router’s admin interface and make sure the port is set to auto-negotiation or gigabit full-duplex—sometimes ports get accidentally locked to 100M.

• Tweak driver parameters
  Some users fixed this issue by adjusting the alx driver’s autonegotiation settings. Create or edit the file /etc/modprobe.d/alx.conf:

  sudo nano /etc/modprobe.d/alx.conf
  

  Add this line to the file:

  options alx autoneg=1
  

  Save the file (Ctrl+O, then Enter) and exit (Ctrl+X). Then update the initramfs and reboot:

  sudo update-initramfs -u
  sudo reboot
  

  After restarting, check the link speed again.

Let me know if any of these steps resolve your issue, or if you need help with any of the commands!

备注：内容来源于stack exchange，提问作者ace05hun