Rpi4 Ethernet Link Goes Down/Up

[6sn7]

Hi All,

I have a Raspberry Pi 4 running Raspian 10. Cat6 cable to a 1GbE switch.
During data transfers to/from the system, the ethernet link sporadically goes down then up.
Does anyone know of a fix for this? I have Rpi3 systems with no network issues.

Below is the logs in /var/log/messages.

kernel: [ 1784.822465] bcmgenet fd580000.genet eth0: Link is Down
kernel: [ 1787.942549] bcmgenet fd580000.genet eth0: Link is Up - 1Gbps/Full - flow control rx/tx

Thanks.

[RaTTuS]

dodgy power ?
dodgy NIC lead
dodgy NIC socket [either end]
dodgy PI

test by swapping components

[6sn7]

Thanks.
I swapped cables and tried different ports on the switch.
Something is funny with my gigabit switch. Other systems work okay. Just the rpi4 has issues.
When I plug the rpi4 into a 100Mb/s switch, all works fine.

[ejolson]

Thanks.
I swapped cables and tried different ports on the switch.
Something is funny with my gigabit switch. Other systems work okay. Just the rpi4 has issues.
When I plug the rpi4 into a 100Mb/s switch, all works fine.

Note that gigabit networking takes more than twice the electricity as 100 Mbit Ethernet. Therefore, you have not fully ruled out the consequences of an inadequate power supply.

What brand of switch are you using?

Would you by chance be using a Rosewill gigabit switch?

My Pi 4B does not work with the Rosewill RC-416 switch. It is now working well with a TP-LINK TL-SG108. More information can be found in

https://www.raspberrypi.org/forums/view ... 1#p1525396

[6sn7]

The power supply is rated at 3.0Amps. I put a scope on it and it shows a solid 5.2vdc with negligible ripple.
The GbE switch is a TRENDnet 8-port Gigabit GREENnet TEG-S80g.

The only other devices attached to the Pi4 is a 7 port USB3.0 hub with its own power supply.
I have 4 USB flash drives RAID-10 which I'm copying files to/from. When connected to a 1GbE switch, I copied 80+ GB of data to it without any issues.
I tried setting the link speed to 100Mb but got a lot of errors, so just staying connected to a 100Mb switch for now.

The CPU temp BTW stays at around 50c (heat sinks on the CPU, Mem and USB chips + cooling fan in the case).

[rjeggens]

I have this too, since I updated my system yesterday. Link up/Link down messages with quite a regular interval. It makes the system fairly unusable. Together with the Aeotec z-wave Stick 5 not working on the Pi 4, makes it a kind of a disappointing SBC.

[ejolson]

I have this too, since I updated my system yesterday. Link up/Link down messages with quite a regular interval. It makes the system fairly unusable. Together with the Aeotec z-wave Stick 5 not working on the Pi 4, makes it a kind of a disappointing SBC.

I bought a new switch and that solved my problem. As long as the new switch was placed between the 4B and the rest of the network, I could still use the old switch for other things. On the other hand, you may have have a different problem, such as a power supply or cable issue.

Note that a cable that worked fine with 100Mbit Ethernet may not with 1Gbit Ethernet, because 1Gbit uses all 8 wires, while only 4 wires are used by 100Mbit.