LAN disconnects after heavy network traffic

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Lincee

Renowned Member
Mar 16, 2015
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I have an issue with some VM's where the LAN disconnects after some heavy network traffic.

For instance, if i download some linux iso's after a while the connections drop. when i go into the vm and try to ping anything (IP based or DNS based, doesnt matter) it fails. all i can do is reboot the vm and then it works again. I tried switching cards, but that doesnt seem to work.

I had it on both an Alpine VM and a Debian VM, strangely enough the proxmox host has no network issues.
 
What speed are these connections? Granted I've had no trouble after getting rid of DHCP in a couple of instances and haven't tried transferring ~1TB of data in/out of a VM yet

I have 3 separately-wired networks - 1Gbit, 2.5Gbit and 10Gbit (MTU 9000, point-to-point, no "switch" except for Proxmox host) and no trouble with VM net disconnections.

Does ' systemctl restart networking ' have any effect in-guest, or is it only a reboot that fixes it? If it was at the physical level I would suspect NIC overheating.

Any messages in journalctl when it cuts out?
 
Could y'all who are having this networking issue post the configs of your VMs somewhere? Not necessarily in the thread, pastebin would do. Never know what commonality might matter for this

I'm firing up a SuSE VM to test iperf3 continuous 10Gbit transfer, will see if it triggers the issue
 
ok, these are things i'll have to check tonight!

Its a selfbuild NAS that used to run Alpine Linux, and i had no issues there. So its somehow connected to Proxmox. Also when i limit the download speed to 15MB/s it seems to hold out longer, so far :)
 
Well, my iperf3 test ran for 136 minutes and change until I finally killed it:

Received ~13TiB
Sent ~5.3TiB

No RX/TX errors, dropped or overruns
DHCP4 lease refreshed (4) times, apparently no issues in journalctl

‍♂️ I'll keep checking the thread, but no issues on my end
 
There's no specific messages when the connections stop. restart networking works.

iperf runs normally within the VM as a client, as well with speeds between 98MB/s & 135MB/s. When i use iperf as a client (again, sinde the VM), it cut out at 101GB with a bitrate of 210 Mbit/sec and i need to restart networking again
 
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Could be a kernel module driver issue, could be overheating, could be the cable, maybe something else. Could be your cat or some RF interference, IDK

What manufacturer is the NIC, what kernel module driver and have you tried replacing the cable (try CAT6) / putting it in a different port on the switch?

Post results of ' lspci |grep -i net '

https://askubuntu.com/questions/46942/how-do-i-stop-my-ethernet-network-connection-from-dropping
(older thread)

https://www.redhat.com/sysadmin/beginners-guide-network-troubleshooting-linux

You may want to consider wiresharking / sniffing the comms, but not sure if that applies here
 
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A kernel driver issue i can accept :) All others i can not. Since this only happens with Proxmox :)

Your second link leads me to this: https://forum.proxmox.com/threads/r...eze-performance-with-promox-7-4-and-8.134212/ which has some more information, same problems :) So i'll see what that does! And lspci:

root@pve:~# lspci | grep -i eth
04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15)

So i think the kernel driver issue is pretty likely the issue :)
 
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in the meantime i tried getting it to work with dkms-8168

now i have no network at all anymore :D im beginning to think going back to Alpine is the better road with this realtek mess :(
 
Kingneutron said:
You could get around it pretty quick by throwing an Intel pcie NIC on the motherboard, or possibly going with USB3 adapter.
Click to expand...

So, i got a USB3 adapter (https://www.tp-link.com/us/home-networking/usb-converter/ue300/ ), only to discover that this also has a Realtek chip :D
Same problems, both an Alpine VM and a Debian VM. so i guess i really have to wait untill i have my intel nic. Ive changed the VM nic from Virtio to Intel E1000 but that didnt help. The Proxmox host itself remains unaffected, network keeps working even though the VM looses connection.
 
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Hi, sorry for resurrecting this old thread, I just would like to know if you've managed to find a solution for this problem.
My device was running fine for couple months but now after a few last updates started to exhibit the "drop of the network" behavior.
None of the 4 VMs do respond. Proxmox admin UI is inaccessible and there re no responses from ping.
This always happen after the backup starts.
The computer has the ASRock Z790M-ITX WIFI board with 2 Intel NICs. 2.5Gb and 1Gb. Only the 1Gb is used.
I've also build another almost identical system (98%), and that one is running fine except it does not have any of the recent 3 updates.

When I pull the network cable and put it back, the whole network thing resets and everything starts to communicate. There were no other actions taken trying that. The only issue is when the backup, followed by PBS, starts the system stops to respond. (SSH does not work either)

I am running Proxmox 8.3.5
 
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6.8.12-11-pve was released for both PVE and PBS, there were some changes to the ABI.
https://git.proxmox.com/?p=pve-kernel.git;a=shortlog;h=refs/heads/bookworm-6.8

ABI stands for Application Binary Interface. It defines the low-level interface between the kernel and its modules (such as device drivers), specifying how compiled code interacts with the kernel at the binary level. This includes details like register usage, memory layout, calling conventions, and symbol versions of exported kernel functions and variables
Click to expand...
 
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