Ubuntu 20.04 Network Performance Extremely Slow

Question

I just upgraded from Ubuntu 18.04 to 20.04 on one of the Dell XPS 13 machines, and the network performance is abhorrent. Internet speed is very fast from a google speed test (>300Mb/s for both upload and download).

However, whenever I try to browse a website or even run sudo apt update the connection will often time out. My internet is very fast on all other devices and I really don't know how to debug this problem.

sudo lshw -class network -short && nmcli device status 

shows

H/W path           Device           Class          Description
==============================================================
/0/100/1c.6/0      wlp2s0           network        Wi-Fi 6 AX200
/3                 br-96f5b790e29e  network        Ethernet interface
/4                 br-15e76fb81c05  network        Ethernet interface
/5                 docker0          network        Ethernet interface

DEVICE           TYPE      STATE         CONNECTION      
wlp2s0           wifi      connected     CSA HQ          
br-15e76fb81c05  bridge    connected     br-15e76fb81c05 
br-96f5b790e29e  bridge    connected     br-96f5b790e29e 
docker0          bridge    connected     docker0         
p2p-dev-wlp2s0   wifi-p2p  disconnected  --              
lo               loopback  unmanaged     --              
gpd0             tun       unmanaged     --             

Solution:

It seems like this is a pretty common problem, and one without a definitive cause. For me, it was because Ubuntu resets the TLP configuration, and the power management went back to "on". I disabled Wi-Fi power management directly by editing:

sudo nano /etc/NetworkManager/conf.d/default-wifi-powersave-on.conf

Then changed the value from 3 to 2, saved changes and rebooted.

I actually got this solution from Reddit and this worked for my case specifically but it seems like it could be caused by a bunch of other things. Read all the proposed solutions below!

Answer 1

The top voted answer didn't solve it for me and I got this solution from a different source.

This was because Ubuntu resets the TLP configuration when I upgraded from 18.04 to 20.04, and the power management went back to "on". I disabled wifi power management directly by editing /etc/NetworkManager/conf.d/default-wifi-powersave-on.conf and changed the value from 3 to 2, saved changes and rebooted.

Instead of rebooting, you can also try running

sudo iwconfig INTERFACE_NAME power off 

where INTERFACE_NAME is the name of your wifi interface. You can find that out by running ip a.

Answer 2

could be the "backport-iwlwifi-dkms" package

I experienced a better performance without this package, so i suggest to remove it

$ sudo apt remove backport-iwlwifi-dkms

this is a known bug

https://bugs.launchpad.net/ubuntu/+source/backport-iwlwifi-dkms/+bug/1869588

Answer 3

I was having the same problem with slow wireless internet speed and what worked for me was to follow the steps proposed in the following post:

Very slow internet connection on ubuntu 16.04

Basically, I edited the file /etc/gai.conf as super user:

sudo nano /etc/gai.conf

Then I looked for the line with precedence ::ffff:0:0/96 100 and removed the # character that preceded it. I had to reboot my system for it to take effect. It worked like a charm.

The funny thing is that when I was using Ubuntu 20.04 Beta, this problem did not happen. Later, when I installed the LTS version, I started having this problem.

Answer 4

Thanks a lot for all information you provided above.

Here I want to tell you about my situation.

I have an XPS-13-9360 (i7-8550U,16G,1T) and manually installed a killer 1650 (aka. intel ax 200). I was facing the same issue, extremely slow wireless connection.

And it seems that the problem has been solved since I installed a linux-5.6.7-generic kernel. (While the last one was 5.4.0-low-latency, I don't know why I installed low latency version, all that I did was do-release-upgrade from Ubuntu 19.10 with 5.3 kernels).

Here I recommend that you install a generic kernel instead of all one (by uname -sr, you can see what kind of kernel you are using), and upgrade to a newer kernel if possible.

BTW, I didn't sacrifice WiFi 6 and it seems OK with Linux 5.6.7

Bests, Leon

Answer 5

Also updated from Ubuntu 18.04 to 20.04 on a Dell XPS 7390, had the same problem, and the accepted solution worked well for a bit (see comments):

sudo nano /etc/NetworkManager/conf.d/default-wifi-powersave-on.conf

I would just add for any other newbies like me that Ctrl + o and then Enter saves the changes made, and Ctrl + x then exits nano mode (https://wiki.gentoo.org/wiki/Nano/Basics_Guide). While here, Ctrl + Alt + t is how you open the terminal where you'd enter all these commands.

My current download speed (compared to a Win10 machine on the same desk) is 87 Kbps (vs. 19Mbps), and upload is 6.7 Mbps (vs. 8.5Mbps).

Answer 6

I had the same problem with an Intel AX200 and Ubuntu 20.04 - extremely slow. Sort of working, but dialup speeds at best.

I updated to the latest Ubuntu mainline kernel build, and now it performs well. This script can make it easy to manage mainline kernel installation and updates.

If you go down this path, consider that it will be up to you to stay on top of security vulnerabilities.

Answer 7

My problem is related to my kernel version. I upgraded with apt (just your usual maintenance) and afterwards my network speeds were incredibly slow.

kernel 5.4 is not supported by killer.

Linux Kernel 5.1 or Linux Kernel 5.3

Use the Intel Wi-Fi 6 AX200 160MHz Firmware while running Linux Kernel 5.1 or 5.3. This will require you to install and use the newer Linux Kernel and copy the Firmware files into your ‘/lib/firmware/‘ folder. You might be able to install a newer Release of your chosen Linux also. For example, Ubuntu 19.10 should work immediately as it installs with Linux Kernel 5.3 and the necessary Firmware.

Newer Linux Kernels like 5.4+ might have bugs and compatibility issues, so if you see issues using them, try downgrading to 5.3

So booting into your older kernel might help. This is a great troubleshooting step and should probably be tried before messing with settings as this doesn't require changing your system.

Answer 8

Deleting the connection, then re-connecting worked for me.

nmcli connection delete <CONNECTION-NAME>
sudo systemctl restart network-manager.service

nmcli supports tab completion. You can list all the available connections by pressing the tab

Then simply re-connect from the UI as you normally would.

Answer 9

Selecting the proprietary wireless driver solved the problem from me.

Steps:

1. Search and open "Additional Drivers"
2. Look for the Wireless Network Adapter driver's entry.
3. Check if the option "Do not use this device" is selected.
4. If yes, select the driver of your computer's network adapter which mentions "(proprietary)" in the end.

Here's how it looks on my machine (second driver - Broadcom)

Answer 10

I've been having nearly the same issue...and across quite a few different linux distributions too. Even with an external USB Wi-Fi adapter on, and my laptop's internal antenna turned off, the signal is basically unusable. I get about 300kbps and a ton of dropped connections. I've tried nearly every online tutorial and terminal command suggestions to fix this, with no luck.

The only solution for me was to download a copy of Windows to do internet browsing. I boot up into Ubuntu for the other stuff. It's not perfect, but Windows doesn't give me any issue whatsoever, even with connection speeds that are good on both my laptop and my USB Wi-Fi. Only real trouble I run into with this solution is updating Ubuntu and being annoyed. Other than that, it works.