Network speed seems limited to 20 mbit/s

[Jolokp]

Kubuntu version: 26.04
KDE Plasma version: 6.6.5

inxi output:

System:
Host: keanu Kernel: 7.0.0-28-generic arch: x86_64 bits: 64
Desktop: KDE Plasma v: 6.6.5 Distro: Kubuntu 26.04 LTS (Resolute Raccoon)
Machine:
Type: Desktop System: Micro-Star product: MS-7E26 v: 1.0
serial: <superuser required>
Mobo: Micro-Star model: B650 GAMING PLUS WIFI (MS-7E26) v: 1.0
serial: <superuser required> Firmware: UEFI vendor: American Megatrends LLC.
v: 1.F0 date: 07/26/2024
CPU:
Info: 8-core model: AMD Ryzen 7 7800X3D bits: 64 type: MT MCP cache:
L2: 8 MiB
Speed (MHz): avg: 4975 min/max: 426/5053 cores: 1: 4975 2: 4975 3: 4975
4: 4975 5: 4975 6: 4975 7: 4975 8: 4975 9: 4975 10: 4975 11: 4975 12: 4975
13: 4975 14: 4975 15: 4975 16: 4975
Graphics:
Device-1: NVIDIA AD104 [GeForce RTX 4070] driver: nvidia v: 595.71.05
Device-2: Advanced Micro Devices [AMD/ATI] Raphael driver: amdgpu
v: kernel
Device-3: Logitech HD Webcam C910 driver: snd-usb-audio,uvcvideo type: USB
Display: wayland server: X.org v: 1.21.1.22 with: Xwayland v: 24.1.10
compositor: kwin_wayland driver: gpu: nv_platform,nvidia,nvidia-nvswitch
resolution: 1: 3440x1440~144Hz 2: 1920x1080~60Hz
API: EGL v: 1.5 drivers: nvidia,radeonsi,swrast
platforms: gbm,wayland,x11,surfaceless,device
API: OpenGL v: 4.6.0 compat-v: 4.5 vendor: nvidia mesa v: 595.71.05
renderer: NVIDIA GeForce RTX 4070/PCIe/SSE2
API: Vulkan v: 1.4.341 drivers: nvidia,radv,llvmpipe surfaces: N/A
Info: Tools: api: clinfo, eglinfo, glxinfo, vulkaninfo
de: kscreen-console,kscreen-doctor gpu: nvidia-settings,nvidia-smi
wl: wayland-info x11: xdriinfo, xdpyinfo, xprop, xrandr
Audio:
Device-1: NVIDIA AD104 High Definition Audio driver: snd_hda_intel
Device-2: Advanced Micro Devices [AMD/ATI] Radeon High Definition Audio
driver: snd_hda_intel
Device-3: Advanced Micro Devices [AMD] Ryzen HD Audio
driver: snd_hda_intel
Device-4: Logitech HD Webcam C910 driver: snd-usb-audio,uvcvideo type: USB
API: ALSA v: k7.0.0-28-generic status: kernel-api
Server-1: PipeWire v: 1.6.2 status: active
Network:
Device-1: Realtek RTL8125 2.5GbE driver: r8169
IF: enp12s0 state: up speed: 1000 Mbps duplex: full mac: d8:43:ae:1f:4c:3a
Device-2: MEDIATEK MT7922 802.11ax PCI Express Wireless Network Adapter
driver: mt7921e
IF: wlp13s0 state: up mac: a8:3b:76:39:1c:6f
Bluetooth:
Device-1: MediaTek Wireless_Device driver: btusb type: USB
Report: hciconfig ID: hci0 state: up address: A8:3B:76:39:1C:70 bt-v: 5.2
Drives:
Local Storage: total: 10.92 TiB used: 151.3 GiB (1.4%)
ID-1: /dev/nvme0n1 vendor: Samsung model: SSD 980 PRO 2TB size: 1.82 TiB
ID-2: /dev/nvme1n1 vendor: Samsung model: SSD 990 PRO with Heatsink 4TB
size: 3.64 TiB
ID-3: /dev/sda vendor: Seagate model: ST6000AS0002-1N917X size: 5.46 TiB
Partition:
ID-1: / size: 3.58 TiB used: 151.3 GiB (4.1%) fs: ext4 dev: /dev/nvme1n1p2
ID-2: /boot/efi size: 299.4 MiB used: 8.1 MiB (2.7%) fs: vfat
dev: /dev/nvme1n1p1
Swap:
ID-1: swap-1 type: file size: 512 MiB used: 34.9 MiB (6.8%) file: /swapfile
Sensors:
System Temperatures: cpu: 60.4 C mobo: 44.0 C gpu: amdgpu temp: 42.0 C
Fan Speeds (rpm): N/A
Info:
Memory: total: 32 GiB note: est. available: 30.45 GiB used: 5.25 GiB (17.2%)
Processes: 417 Uptime: 22m Shell: Bash inxi: 3.3.40


Hello everyone!

I have just decided to move away from Windows 11 and installed Kubuntu on my PC. My previous experience with Ubuntu on other systems has been smooth, but now my network speed seems to be limited to about 20 mbit/s. Doesn't matter if I use a wired or wireless connection or how many processes try to use the connection, the speed seems to be artificially limited to 20 mbit/s. Speedtest.net shows the speeds I'm used to and my router doesn't seem to have a problem either. This wasn't a problem under Windows, so I'm guessing it's some sort of driver issue? I'm still pretty new to the inner workings of Linux, so excuse any rookie mistakes. I'd appreciate any help, thanks in advance.

Joris

[oshunluvr]

If both network devices are running that slow, it's likely not a device driver because they are different devices and use different drivers. Seems more like a larger networking issue.

However, if speedtest shows normal speeds then your browser is getting a full speed connection.

I've seen no reports of this occurring from other users. What is it - specifically - that you are doing that leads you to believe your speed is that slow?

[die.boer]

what is you're speed suppose to be ?
which applications are stuck at ~20 Mbps (browser, Steam, apt, torrents, all downloads)?
don't think it's a driver issue.
please install this

snap install speedtest

then run

speedtest

and post the output here
also post output of these 3

tc qdisc show

ip link

sudo ethtool -i enp12s0​

[claydoh]

Realtek RTL8125 2.5GbE driver: r8169

This may be the issue, assuming it is the wired connection; you might have better luck trying the "matching" driver for this card.

sudo apt install r8125-dkms

[Jolokp]

First of all thank you for all your replies. I noticed the problem when downloading Steam games, but downloads via the browser also seem to have the same limit. Steam also shows higher available speeds in the download view, but it's still limited to 20 mb/s. Most confusing for me was the system montitor clearly capping out at 20, never going above. While under load it's just a straight line at 20 MiB/s.

Ookla Speedtest console output:

Server: Deutsche Telekom - Dusseldorf (id: 74096)
ISP: Deutsche Telekom AG
Idle Latency: 4.07 ms (jitter: 0.16ms, low: 3.98ms, high: 4.21ms)
Download: 103.34 Mbps (data used: 185.7 MB)
20.77 ms (jitter: 9.34ms, low: 4.13ms, high: 45.07ms)
Upload: 71.54 Mbps (data used: 34.8 MB)
9.52 ms (jitter: 5.25ms, low: 4.00ms, high: 26.44ms)
Packet Loss: Not available.
Result URL: https://www.speedtest.net/result/c/6...5-cee383efde92

tc qdisc show:

qdisc noqueue 0: dev lo root refcnt 2
qdisc fq_codel 0: dev enp12s0 root refcnt 2 limit 10240p flows 1024 quantum 1514 target 5ms interval 100ms mem
ory_limit 32Mb ecn drop_batch 64
qdisc noqueue 0: dev wlp13s0 root refcnt 2

ip link:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp12s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen
1000
link/ether d8:43:ae:1f:4c:3a brd ff:ff:ff:ff:ff:ff
altname enxd843ae1f4c3a
3: wlp13s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DORMANT group default qlen
1000
link/ether a8:3b:76:39:1c:6f brd ff:ff:ff:ff:ff:ff
altname wlxa83b76391c6f


sudo ethtool -i enp12s0 (after trying claydoh's suggestion, although I'm not sure I did it right, inxi output is still the same):

driver: r8169
version: 7.0.0-28-generic
firmware-version: rtl8125b-2_0.0.2 07/13/20
expansion-rom-version:
bus-info: 0000:0c:00.0
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: yes
supports-priv-flags: no

Sorry if my english is a bit clunky, it's my second language. Thanks again for your help.

Joris

[die.boer]

everything from the outputs looks ok
what i do see is that speedtest use Mbps = Megabits per second , and linux applications (Steam, browsers, KDE System Monitor) often use MB/s or MiB/s = Megabytes per second
(1 Byte = 8 bits)
now your speedtest shows 103.34 Mbps,that means your internet connection is downloading at approximately:103 ÷ 8 = 12.9 MB/s
so if Steam is downloading at around 12-13 MB/s, your system is actually performing exactly as expected

System Monitor clearly capping out at 20 MiB/s.

Because 20 MiB/s is actually: 20 × 8 = 160 Mbps

i know it's a bit confusing...

Here's an easy test:
Start downloading a game in Steam.
Open KDE System Monitor

• Take a screenshot of:
• Steam's download graph.
• KDE System Monitor's network graph
• If Steam says:12 MB/s , then everything is working correctly. If it says: 2 MB/s , then you do have a problem.