[Solved] Raspberry Pi 4 Ethernet Problem

[johnnywho]

I'm having an ethernet connectivity problem on a freshly installed Raspbian Buster Lite (2019-07-10)

I'm able to find the rpi4 on the network, but ssh is slow to connect and feels very laggy when typing.
DNS doesn't work out of the box. After specifying it manually, rpi4 finds the servers, but the speed is terribly slow ~1kb/s and connection often gets interrupted.

I tried WiFi, which works well, but my intended setup requires an ethernet connection. I used different cables, checked settings on my router, restarted it, but problem still persisted.
I swapped the same system on a sd card into my older raspberry pi 3b+ and it works without any problem – full speed no lag.

I decided to ask for replacement unit, but the new one I've got has the same problem.
This leads me to the conclusion that it's an issue related to my router.
Since I can't replace it, and my older rpi3b+ works well in that setup, I'm hoping some on this forum could help me finding a workaround to this issue.

[neilgl]

What happens if you temporarily unplug the Ethernet cable from the 3b+ and put it into the pi4?

[johnnywho]

What happens if you temporarily unplug the Ethernet cable from the 3b+ and put it into the pi4?

Hot-swapping the cables doesn't fix it. SSH still laggy, server names still not found.

What's worth noting is that I also tried static ip configurations which didn't help much as well.

[trejan]

What brand/model switch is it?

Run "ifconfig". Are the error counters for eth0 all zero?

[johnnywho]

It's a rather unknown docsis 3.0 modem/router Technicolor EPC3940 from my cable provider.

I tested static ip config, with manually entered `static domain_name_servers=` in `/etc/dhcpcd.conf`. Pings seem low, but I had to wait 20 seconds to see the first ping result:

Code: Select all

pi@raspberrypi:~ $ ping google.com
PING google.com (216.58.207.78) 56(84) bytes of data.
64 bytes from 216.58.207.78: icmp_seq=2 ttl=53 time=13.7 ms
[redacted]....
64 bytes from 216.58.207.78: icmp_seq=22 ttl=53 time=14.5 ms
^C
--- google.com ping statistics ---
22 packets transmitted, 9 received, 59.0909% packet loss, time 760ms
rtt min/avg/max/mdev = 13.690/14.929/18.509/1.335 ms

Next ping command I tried has failed with an error:

Code: Select all

pi@raspberrypi:~ $ ping google.com
ping: google.com: Temporary failure in name resolution

Although no RX/TX errors in the `ifconfig` output:

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pi@raspberrypi:~ $ ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.0.67  netmask 255.255.255.0  broadcast 192.168.0.255
        inet6 fd51:42f8:caae:d92e::ff  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::230e:5e0e:48d:2718  prefixlen 64  scopeid 0x20<link>
        ether dc:a6:32:12:fa:29  txqueuelen 1000  (Ethernet)
        RX packets 1422  bytes 140621 (137.3 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1030  bytes 136602 (133.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[drgeoff]

Looks like you are losing lots of incoming packets. Repeat the ping test but to the IP of the router/modem.

[johnnywho]

You were right, it loses packets when pinging the router.

Code: Select all

 pi@raspberrypi:~ $ ping 192.168.0.1 -c 8
PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
64 bytes from 192.168.0.1: icmp_seq=1 ttl=64 time=1.27 ms
64 bytes from 192.168.0.1: icmp_seq=6 ttl=64 time=1.42 ms
64 bytes from 192.168.0.1: icmp_seq=7 ttl=64 time=0.814 ms

--- 192.168.0.1 ping statistics ---
8 packets transmitted, 3 received, 62.5% packet loss, time 236ms
rtt min/avg/max/mdev = 0.814/1.168/1.417/0.257 ms

I plan to test it with different router on a different network, but that won't solve my problem at all.
What could be the reason that rpi3b+ works fine but two rpi4 units, all tried with the same sd card, are not working on my network?

[drgeoff]

Edit their dhcpcd.conf files to give each RPi a static address. Connect them together with an ethernet cable. (Crossover cable not required.) Do the ping tests. If not losing packets, time to look more closely at the router. If losing packets something up with the RPi4B.

[cpunk]

Wow, this is exactly like my situation (thread over here).

I have an "EPC3940ADL EuroDocsis 3.0 2-PORT Voice Gateway" acting as my router, and I experienced packet losses of approximately 40%.

Static IP didn't help. Disabling IPv6 didn't help. I presume the ethernet interfaces try to reach gigabit speed, but start losing packets / frames at that speed.

I temporarily switched to WiFi and disconnected from Ethernet to suppress the problem. Since WiFi is overcrowded here, I am intending to add a separate WiFi router/switch to my network today.

[epoch1970]

Looks like this is a Cisco device, rebranded by ISPs.
Found a user guide at random on the Internet, found nothing obvious.
(Seems to operate as modem router only, not a bridged modem.)

[cpunk]

Update: I put a TP-Link wireless router downstream of it ( with routing functionality disabled in the TP-Link, so essentially my TP-Link is a switch with antennas or an access point ). Raspberries started working fine, even ping -f loses no packets.

Seems to be a compatibility issue with these Cisco devices.

[HawaiianPi]

You should see if it's possible to set the ISP supplied modem/router gateway into bridge mode, then connect a better router.

A few years ago I was in a rental with an ISP supplied gateway that was crap. Their tech support said it wasn't possible to set their router/modem device into bridge mode, but after some searching I found it was possible. After setting the ISP gateway to bridge mode and connecting my own router, it got an external IP and everything worked great.

Or check with the ISP to see if they have a modem only device with an Ethernet jack (my old cable TV ISP had modems without routers).

[johnnywho]

The problem turned out to be compatibility issue between rpi4 and my ISP branded Cisco router.

I connected my rpi4 to another network with a gigabit switch and immediately noticed an improvement during connecting and typing commands over ssh. No ping packet losses and decent internet speeds when using speedtest-cli. I connected an external usb3 hdd and tried transferring files over smb (~35MBytes/s) and sftp (~40MBytes/s). Not a gigabit-speed, but still an usb3 upgrade that I wanted to achieve.

I know that with a bit of hack I can trick my router into bridge mode and put a new router behind it, but that's rather a workaround to my problem. I will try to persuade my ISP to let me use a third-party modem/router which I was planning to buy for some time now (my current EPC3940 drops wifi speed over short range).

It's still a bit disappointing since this is not a purely hardware problem. After all, rpi3b+ works perfectly all this time, which leaves the only possibility that rpi4 uses different mode or parameters that cause the incompatibility. I strongly believe there should be a way to change them on the rpi4 itself without the need of the new hardware.

If someone has any suggestions what config options can potentially work as a fix, please post it here, I'll be glad to try it out.

Anyways, thanks guys for all your help so far.

[sniegu.pl]

Hi,

You can force the connection to be 100Mbps instead of 1Gbps as a workaround. It's handicap but IMHO better than switching to wifi and fighting for radio resources with other devices in the network.

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# ethtool -s eth0 speed 100 duplex full

[hiox]

Hi there!

I've noticed the same problem. I have Cisco router and ssh connection to my Pi4 4gb over Ethernet Is extremely slow and lagging. Once wifi was setup everything works nice. Is there any solution to this?

Thanks!

[Mike_333]

Same thing, upc connect box (compal ch7465lg), when enabled 1000mb - lost packets, when enabled 100mb - all is good
temporary solution enable 100mb at startup:

crontab -e

add
@reboot sleep 10 ; /sbin/ethtool -s eth0 speed 100 duplex full

[stefan9717]

same Problem here, but with different hardware:

switch is a hp1810G-24, the first rpi is a pi4b with 4gb ram. It all works ok with a 1 gbit connection.
Yesterday I added a second pi, a pi3b+, that has usb tv dongle (hauppauge wintv dual hd), and that is connected to the cable-installation in the house. As soon as i connected the network cable on the pi3b+, the lan connection on the pi4b was completely dead, no lights blinking anymore at the lan port.

Is there any trick how I can operate both pi's with lan connection?


update 20200620: my problem was probably caused by a broken network cable.

[johnnywho]

Good news, one of the recent software updates apparently fixed the problem.

I kept using my raspberry pi 3b+ having rpi 4 back in the box waiting for a router upgrade. I tried to swap the sd card from time to time and check if something has changed, especially after the rpi-eeprom upgrades. This time around I was surprised to see rpi 4 ssh connecting noticeable faster with very good responsiveness. Further tests proved that it works flawlessly over gigabit connection and since then it has replaced my rpi 3b+ on my local network to run 24/7 without any issues so far.

[yb62]

I have the same problem on my raspberry pi 4 4gb.
the netspeed is not good
i updated the raspberry but always not good

[fruitoftheloom]

I have the same problem on my raspberry pi 4 4gb.
the netspeed is not good
i updated the raspberry but always not good

The Original Poster has SOLVED his issue, so the problem is not the same

[RGJ-PI]

I have the same problem on my raspberry pi 4 4gb.
the netspeed is not good
i updated the raspberry but always not good

Looks like you have a different problem then. Please open a new topic with additional information about your specific issue.