[SOLVED] System loses networking

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paulmorabi

Member
Mar 30, 2019
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Hi,

I'm using the latest Proxmox on a Ryzen 2700. I've been running two Windows VM's very stable for a long while now. I suddenly noticed I couldn't connect remotely and thought the system had crashed so rebooted. After checking the disk via smartctl, fsck etc. I discovered that its the networking that is dropping out.

If I start one Windows VM, it boots and I can log in but there is no network access in the VM even though Windows reports it is fine. Likewise, Proxmox host itself seems to disconnect from the network and stops responding to pings. I've tried tailling the syslog but nothing useful seems to be appearing.

Even without starting a VM and doing an "apt update" will cause the network to drop out. I lose external access (via ping, ssh and also web).

Any ideas what could be causing this?

Code: 
root@pve:~# pveversion -v
proxmox-ve: 7.0-2 (running kernel: 5.11.22-3-pve)
pve-manager: 7.0-11 (running version: 7.0-11/63d82f4e)
pve-kernel-5.11: 7.0-6
pve-kernel-helper: 7.0-6
pve-kernel-5.4: 6.4-4
pve-kernel-5.11.22-3-pve: 5.11.22-6
pve-kernel-5.11.22-2-pve: 5.11.22-4
pve-kernel-5.11.22-1-pve: 5.11.22-2
pve-kernel-5.4.124-1-pve: 5.4.124-1
pve-kernel-5.4.34-1-pve: 5.4.34-2
ceph-fuse: 14.2.21-1
corosync: 3.1.2-pve2
criu: 3.15-1+pve-1
glusterfs-client: 9.2-1
ifupdown: 0.8.36
ksm-control-daemon: 1.4-1
libjs-extjs: 7.0.0-1
libknet1: 1.21-pve1
libproxmox-acme-perl: 1.2.0
libproxmox-backup-qemu0: 1.2.0-1
libpve-access-control: 7.0-4
libpve-apiclient-perl: 3.2-1
libpve-common-perl: 7.0-5
libpve-guest-common-perl: 4.0-2
libpve-http-server-perl: 4.0-2
libpve-storage-perl: 7.0-10
libqb0: 1.0.5-1
libspice-server1: 0.14.3-2.1
lvm2: 2.03.11-2.1
lxc-pve: 4.0.9-4
lxcfs: 4.0.8-pve2
novnc-pve: 1.2.0-3
proxmox-backup-client: 2.0.8-1
proxmox-backup-file-restore: 2.0.8-1
proxmox-mini-journalreader: 1.2-1
proxmox-widget-toolkit: 3.3-6
pve-cluster: 7.0-3
pve-container: 4.0-9
pve-docs: 7.0-5
pve-edk2-firmware: 3.20200531-1
pve-firewall: 4.2-2
pve-firmware: 3.2-4
pve-ha-manager: 3.3-1
pve-i18n: 2.4-1
pve-qemu-kvm: 6.0.0-3
pve-xtermjs: 4.12.0-1
qemu-server: 7.0-13
smartmontools: 7.2-pve2
spiceterm: 3.2-2
vncterm: 1.7-1
zfsutils-linux: 2.0.5-pve1
 
Last edited:
After spending hours googling and looking at logs, I ended up finding a similar issue reported in Ubuntu forums. After rebooting my router, everything magically started working again. Must have been a weird network/routing issue.
 
I'm having the same issue. After 8min network goes offline. Only solution is reboot.
No idea what is hapening. Disabled the firewall still issue.
 
it's 2023 now and i'm having the same problem. I have 2 vm's and 1 lxc running on proxmox and every 4 to 5 hours my whole proxmox instance loses network so that means all my vm's and lxc also lose network. The only way to fix it is to reboot the whole system and then after 4 to 5 hours it happens again. The first 4 months of using proxmox it was all fine but now this problems keeps happening and i have no idea how to fix it.... anyone that has the same problem and could help?
 
I now also loose connection over ethernet NICs after some hours of work. Which is a problem for iSCSI storage. I can see storage not online in syslog. But can not find RC. I created as workaround a 2nd LUN and use a separate VLAN now which seems to be more stable than the first LUN using my normal network. But when I try to move Hard Disks over it fails after 60% and vmbr0 does not reach my Synology storage anymore. Local ping on the PVE can reach IP. Pings from other VMs fail. This worked stable several month. Any idea?!?

Proxmox VE 7.3-6 x86_64, ProLiant DL360 Gen9, Kernel 5.15.102-1-pve
 
For me it was another server in the same switch. After a while I found out that my old MacMini server had very long ping times to the switch. A reboot fixed it and since then the iSCSI connection works stable again. So it was not related to ProxMox NICs or Linux bridge.
 
Hi all,

I also encountered this issue and stumbled upon this forum post. I ended up fixing the issue - for me I had not added a Linux VLAN to the network configuration for the node, despite the node actually being on that VLAN (tagged, configured by port on my router). My fix specifically was:

  1. Goto PVE node webpage
  2. Select the node -> 'Network'
  3. "Create" -> Linux VLAN
  4. Change the name to vmbr0.xx (where xx is your vlan tag)
  5. Configured the rest of the fields according to your network
If you royally screwed your network somehow and can't even access your nodes webpage, you can try manually editing the interfaces file, although it is not recommended.

nano /etc/network/interfaces
It should look something like this:


code_language.shell: 
auto lo
iface lo inet loopback

iface <controller id> inet manual

auto vmbr0
iface vmbr0 inet manual
    bridge-ports <controller id>
    bridge-stp off
    bridge-fd 0
    bridge-vlan-aware yes
    bridge-vids 2-4094

auto vmbr0.xx
iface vmbr0.xx inet static
    address <ip address>
    gateway <your vlan gateway>
#Name of this VLAN

source /etc/network/interfaces.d/*
 
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