limited internet speed

[1mint80]

Hi. This is my first post on this forum. Thank you for having me
I usually google my problems until I find a solution but this one has been bugging me for years and now after a lot of attempts at fixing it and equal times of giving up, I'm trying your help. Especially because this might have a very easy solution and I don't want to spent more hours on this.
I have a 2014 desktop computer with Ethernet only. I've always had Linux on it. Internet speed used to be normal. This has changed but I did not really take notice at the time so I don't know what change made this happen. No hardware changes were made. My maximum speed has been around 8.5 Mbps for a couple of years now. If I plug the UTP-cable into my laptop, internet speed is 3 times faster. The same version of Linux Mint was installed on both computers with default internet connection settings.
I've updated my BIOS yesterday and upgraded to Linux Mint 20 hoping this would fix the problem but to no avail.
I've tried different solutions but did not write them down so I'm afraid I can't recall them.

I have no idea what other information you need to assess this problem, so I just put some basic information below.

lspci output:

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03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 11)

driver:

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/sys/bus/pci/drivers/r8169/0000:03:00.0

ethernet settings:

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sudo ethtool enp3s0 
[sudo] password for ***:                    
Settings for enp3s0:
	Supported ports: [ TP MII ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Supported pause frame use: Symmetric Receive-only
	Supports auto-negotiation: Yes
	Supported FEC modes: Not reported
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Advertised pause frame use: Symmetric Receive-only
	Advertised auto-negotiation: Yes
	Advertised FEC modes: Not reported
	Link partner advertised link modes:  10baseT/Half 10baseT/Full 
	                                     100baseT/Half 100baseT/Full 
	                                     1000baseT/Full 
	Link partner advertised pause frame use: Symmetric
	Link partner advertised auto-negotiation: Yes
	Link partner advertised FEC modes: Not reported
	Speed: 1000Mb/s
	Duplex: Full
	Port: MII
	PHYAD: 0
	Transceiver: internal
	Auto-negotiation: on
	Supports Wake-on: pumbg
	Wake-on: d
	Current message level: 0x00000033 (51)
			       drv probe ifdown ifup
	Link detected: yes

[antikythera]

You may have the wrong MTU value set for the connection. I know my realtek cannot handle 1500 which is the linux default. Use the following command to test the theory. If you get an error, it will tell you the safe maximum to use instead.

ping -s 1472 9.9.9.9

1472 in this command is equal to max MTU of 1500 because 28 bytes are reserved. Press CTRL+C to stop the ping.

Sample output:

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ping -s 1472 9.9.9.9
PING 9.9.9.9 (9.9.9.9) 1472(1500) bytes of data.
From 192.168.1.254 icmp_seq=1 Frag needed and DF set (mtu = 1492)
1480 bytes from 9.9.9.9: icmp_seq=2 ttl=56 time=19.8 ms
1480 bytes from 9.9.9.9: icmp_seq=3 ttl=56 time=26.1 ms
1480 bytes from 9.9.9.9: icmp_seq=4 ttl=56 time=18.7 ms
1480 bytes from 9.9.9.9: icmp_seq=5 ttl=56 time=18.1 ms
1480 bytes from 9.9.9.9: icmp_seq=6 ttl=56 time=20.5 ms
1480 bytes from 9.9.9.9: icmp_seq=7 ttl=56 time=20.0 ms
1480 bytes from 9.9.9.9: icmp_seq=8 ttl=56 time=18.6 ms
1480 bytes from 9.9.9.9: icmp_seq=9 ttl=56 time=36.8 ms
1480 bytes from 9.9.9.9: icmp_seq=10 ttl=56 time=35.7 ms
^C
--- 9.9.9.9 ping statistics ---
10 packets transmitted, 9 received, +1 errors, 10% packet loss, time 20ms
rtt min/avg/max/mdev = 18.145/23.823/36.767/7.013 ms

This tells me to use an MTU value of 1492 instead of 1500 on my network settings page. DO NOT change negotation type from Ignore or Auto to set the value manually. It will stop the adaptor recognising the cable most likely. It does with my PC using the same adaptor as you.

[1mint80]

Hi, thanks for the fast reply.
I'm afraid that line is missing in my output. Any other way of retrieving that value?

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ping -s 1472 9.9.9.9
PING 9.9.9.9 (9.9.9.9) 1472(1500) bytes of data.
1480 bytes from 9.9.9.9: icmp_seq=1 ttl=56 time=162 ms
1480 bytes from 9.9.9.9: icmp_seq=2 ttl=56 time=21.7 ms
1480 bytes from 9.9.9.9: icmp_seq=3 ttl=56 time=20.3 ms
1480 bytes from 9.9.9.9: icmp_seq=4 ttl=56 time=17.3 ms
1480 bytes from 9.9.9.9: icmp_seq=5 ttl=56 time=19.0 ms
1480 bytes from 9.9.9.9: icmp_seq=6 ttl=56 time=18.1 ms
1480 bytes from 9.9.9.9: icmp_seq=7 ttl=56 time=26.3 ms
1480 bytes from 9.9.9.9: icmp_seq=8 ttl=56 time=20.3 ms
1480 bytes from 9.9.9.9: icmp_seq=9 ttl=56 time=23.0 ms
^C
--- 9.9.9.9 ping statistics ---
9 packets transmitted, 9 received, 0% packet loss, time 8012ms
rtt min/avg/max/mdev = 17.323/36.399/161.601/44.338 ms

[antikythera]

If it is missing then 1500 is probably okay for your internet connection. Try it again though later just in case because it is possible for the packet transfer success or failure value to fluctuate. I got 1492 confirmed after testing over a few days at different times.

[1mint80]

I've tested it several times but it did not show, so I'll indeed assume 1500 is OK.

(anyone else) other ideas?

[senjoz]

Maybe some bandwidth limiter or QoS setting in the router limits wan speed for desktop computer.

Regards,
Jože

[1mint80]

Settings on the modem are very basic. Also I am the only one who has access and I don't think my ISP targeted my desktop
Thanks for the reply.
I'll try to find an external network card to test if that makes a difference. Don't let this in the meantime stop you from making suggestions.

[senjoz]

I've updated my BIOS yesterday and upgraded to Linux Mint 20 hoping this would fix the problem but to no avail.

Did you upgrade to LM20 or fresh install? Did you try internet speed if the desktop computer is booted from a live installation USB stick?

Settings on the modem are very basic. Also I am the only one who has access and I don't think my ISP targeted my desktop

Is it only modem or is it a router? Did you try with another port on modem-router? Could you describe your network more precisely? Are both, download and upload, speeds impaired? Is network speed in LAN also impaired? Do you use VPN or TOR? Is some background internet process active?

Regards,
Jože

[1mint80]

Did you upgrade to LM20 or fresh install? Did you try internet speed if the desktop computer is booted from a live installation USB stick?

Fresh install, same issue if I boot from a live USB.

Is it only modem or is it a router? Did you try with another port on modem-router? Could you describe your network more precisely? Are both, download and upload, speeds impaired? Is network speed in LAN also impaired? Do you use VPN or TOR? Is some background internet process active?

If I plug the same cable into my laptop, it's a lot faster so I don't think this is a modem/network issue, no?

Ookla speedtest on desktop:
PING 10 ms
DOWNLOAD 9.39 Mbps
UPLOAD 7.98 Mbps

on laptop:
PING 16 ms
DOWNLOAD 85 Mbps
UPLOAD 9.46 Mbps

ISP max. download speed is 100Mbps, upload 10 Mbps. It might affect upload speed but not sure.

No VPN/TOR/background process.

There is another issue with the internet connection. If I start up my computer (or plug in the LAN cable), most times there is no internet connection. The system keeps trying to connect with the cable, but it switches between 'cable unplugged' and 'connecting'. This does not always happens, sometimes it finds the connection after a few tries, sometimes it takes 5-10 minutes. This is of course also a problem, but as this also happens on my laptop, it seems it is not related to the speed issue.

I bought a new network card yesterday. As you might've guessed, it did not solve my problem.

[senjoz]

Have your devices, desktop and laptop, private or public IP addresses? You can check it with ifconfig.

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ifconfig

If your devices have public IP addresses then you have modem, not router. Maybe your ISP limits speed for the IP or MAC address of your desktop but not for your laptop, no matther which network cable you use. In that case the solution to your problem could be contacting your ISP.

Regards,
Jože

[1mint80]

It's a modem/router (Compal CH7465LG-TN).
My devices have private addresses. I guess my ISP can still limit the speed for my desktop via MAC-address so I'll contact them, just to eliminate it.

[senjoz]

You can verify network connection quality of the desktop computer with iperf3. Connect both computers, the desktop and the laptop, with network cables to the router. With Synaptic Package Manager install iperf3 on both computers. With ifconfig determine IP addresses of ethernet ports. On one computer (laptop) run in terminal next command

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iperf3 -s

On another computer (destop) run in terminal next command

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iperf3 -c 192.168.1.150 -i 1 -t 13 -P 4 -O 3

Instead 192.168.1.150 insert IP address of iperf3 server (laptop ethernet IP address). After 13 seconds the last two lines will show you sending and receiving speeds. If all your devices (laptop, router and desktop) have gigabit ethernet, the results should be close to 1000 Mbits/sec. You can learn more about iperf3 on https://iperf.fr/iperf-doc.php .

If the above test will confirm that the ethernet port in the desktop is working okay (link between the desktop and the router is okay), I would suggest to check again router configuration for settings that restrict connection speed of the desktop computer to the wan network to 10 Mbps and also to contact your ISP. If you got the modem+router device from ISP, they should help you. Waiting 10 minutes for a connection establishment is strange.

Regards,
Jože


EDIT: Did you try to reset the modem/router? Is any firmware update available for modem/router?

[1mint80]

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iperf3 -c 192.168.0.146 -i 1 -t 13 -P 4 -O 3
Connecting to host 192.168.0.146, port 5201
...
[SUM]   0.00-13.00  sec  14.5 MBytes  9.35 Mbits/sec  535             sender
[SUM]   0.00-13.00  sec  14.6 MBytes  9.42 Mbits/sec                  receiver
iperf Done.

This is far from 1000 Mbits/sec

If I go to my netwerk settings on my desktop, it states: Ethernet (enp6s0) connected - 100 Mb/s. On my laptop it's 1000 Mb/s.

Modem reset doesn't do anything. Firmware update happens automatically.
ISP told me they do not limit the speed of single devices.

[sleeper12]

You can try:

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 sudo systemctl restart network-manager.service 

[1mint80]

Does nothing for the transfer speed. Will try the command next time it keeps trying to connect. Thank you.

[sleeper12]

Maybe reload the driver:

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 sudo modprobe -r r8169 && sudo modprobe r8169 

[deepakdeshp]

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iperf3 -c 192.168.0.146 -i 1 -t 13 -P 4 -O 3
Connecting to host 192.168.0.146, port 5201
...
[SUM]   0.00-13.00  sec  14.5 MBytes  9.35 Mbits/sec  535             sender
[SUM]   0.00-13.00  sec  14.6 MBytes  9.42 Mbits/sec                  receiver
iperf Done.

This is far from 1000 Mbits/sec

If I go to my netwerk settings on my desktop, it states: Ethernet (enp6s0) connected - 100 Mb/s. On my laptop it's 1000 Mb/s.

Modem reset doesn't do anything. Firmware update happens automatically.
ISP told me they do not limit the speed of single devices.

ISP may limit the speed in total for all the devices connected to the router. In my case I have a fast download speed only for 2GB, later the downloads are with reduced speed.

[senjoz]

I'll try to find an external network card to test if that makes a difference.

I bought a new network card yesterday. As you might've guessed, it did not solve my problem.

What type of network card you bought? Are iperf3 results with this card similar?

There is another issue with the internet connection. If I start up my computer (or plug in the LAN cable), most times there is no internet connection. The system keeps trying to connect with the cable, but it switches between 'cable unplugged' and 'connecting'. This does not always happens, sometimes it finds the connection after a few tries, sometimes it takes 5-10 minutes. This is of course also a problem, but as this also happens on my laptop, it seems it is not related to the speed issue.

That is really strange. Obviously there are difficulties with negotiation between network ports. It must be related to the speed problem. Maybe network switch in modem/router is problematic.

Did you try different ports on modem/router, did you try different patch cables? Can you see something suspicious in modem/router logs or logs on the desktop (journalctl -b or journalctl -b | grep network or journalctl -b | grep enp3s0 or journalctl -b -p3)?

If you have, or can borrow, a gigabit ethernet switch, you could try to use it between the modem/router and both computers. Then you could repeat iperf3 test omitting possible problematic network switch in modem/router and so verify that the network card in the desktop is okay. But, that would not be the solution to your problem.

Workaround would be to use the wireless network, if it is working okay.

Regards,
Jože

[SMG]

I found two other threads on this forum, one from 2013 and one from 2014, with the exact same issue with the same card and no solution. I found a number of threads on other forums with issues with this particular card. The card is apparently known to be troublesome.

This thread from 2018, Realtek RTL8111/8168/8411 Ethernet Controller - r8168 driver install, r8169 driver doesn't work, mentions getting a driver from Realtek and has instructions. Both the link for the driver and the instructions still seem to be working.

This thread from 2015, [Solved] Realtek RTL8111/8168/8411 connection issues explains how the poster manually set up static IP addresses, etc. to get it to work properly.

Hopefully one of these will help.

[antikythera]

This thread from 2018, Realtek RTL8111/8168/8411 Ethernet Controller - r8168 driver install, r8169 driver doesn't work, mentions getting a driver from Realtek and has instructions. Both the link for the driver and the instructions still seem to be working.

Hopefully one of these will help.

Thanks, just tried this one out of interest to see if I could get it working with LMDE4 and if it was any better with my hardware. There's a new driver build for 2020 and it certainly does make a difference to my GA-AM1M-S2H onboard realtek controller.

I took a Timeshift snapshot first, while my system reported the correct speeds with ifconfig -a and speedtest with r8169, it's noticeably more responsive when browsing the web using the proprietary r8168. The acid test will be whether or not it stays active. I had no cutting out like some do with r8169 but you never know...

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Network:
  Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet 
  vendor: Gigabyte driver: r8168 v: 8.048.03-NAPI port: d000 bus ID: 02:00.0 
  IF: enp2s0 state: up speed: 1000 Mbps duplex: full mac: you don't need to see that ;)

The script included automatically blacklisted r8169 but I have now uninstalled the debian firmware-realtek package to get rid of it completely. I knew it lagged a bit more than W7 and W10. I just accepted it as a quirk of the bundled kernel driver and shouldn't have evidently.