Fix Slow Internet Speed on Debian Testing Solving

Fixing System

Fixing Ethernet Slow Speed

2. 2. Installing Requirement

   Then to Install Required Software for Ethernet
   Run:

   sudo apt install ethtool

   Authenticate with the User Admin Password.
   If Got “User is Not in Sudoers file” then see:
   How to Enable sudo.

3. 3. Looking up Interface ID

   Find out your Ethernet Device ID
   Simply play:

   ifconfig -a

   In the output, you should recognize your Ethernet Interface, for example: enp4s0

4. 4. Fixing Ethernet Interface

   Now to Fix Ethernet Speed and Duplex
   Run:

   sudo ethtool -s [DEVICEID] speed 1000 duplex full autoneg on

   Example:

   sudo ethtool -s enp4s0 speed 1000 duplex full autoneg on

   Auto-Negotiation allows the device to choose the best performance mode based on its counterpart.
   Full-duplex enables simultaneous sending and receiving of packets.

Thanks to:
phoenixnap.com

Fixing Wi-Fi Slow Speed

5. 5. Identify Wi-Fi Interface

   First, find your Wi-Fi Device ID:

   iw dev

   Look for the line beginning with Interface, for example: wlp2s0

6. 6. Disable Wi-Fi Power Saving

   To avoid performance drops, disable Wi-Fi Power Management:

   sudo iw dev [DEVICEID] set power_save off

   Example:

   sudo iw dev wlp2s0 set power_save off

   To make it permanent:

   sudo bash -c 'echo "ACTION=="add", SUBSYSTEM=="net", KERNEL=="wlp*", RUN+="/usr/bin/iw dev %k set power_save off"" > /etc/udev/rules.d/70-wifi-powersave.rules'

7. 7. Check Wi-Fi Bitrate

   Verify your Wi-Fi Bitrate:

   iwconfig

   Look for Bit Rate= value.
   If it’s low (e.g. 54 Mb/s), you might have interference or wrong band.

8. 8. Restart and Reassociate Wi-Fi

   Reset and reconnect your wireless interface:

   sudo nmcli device disconnect [DEVICEID] && sudo nmcli device connect [DEVICEID]

   Example:

   sudo nmcli device disconnect wlp2s0 && sudo nmcli device connect wlp2s0

9. 9. Force 5GHz Band (if Supported)

   To avoid 2.4GHz interference, prefer 5GHz Band:

   nm-connection-editor

   Then navigate to Wi-Fi → Band → A (5GHz) and Save.

10. 10. Update Wi-Fi Firmware and Drivers

    Finally, update Wi-Fi Firmware and Drivers:

    sudo apt update && sudo apt install --reinstall linux-firmware

    sudo ubuntu-drivers autoinstall

    Then reboot:

    sudo reboot

Thanks to: phoenixnap.com