Network IF only goes up after unplug/replug

RobJ97

New Member
Oct 30, 2025
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Hello!
I have an issue that is literally driving me insane. I have installed Proxmox on a machine that has a 10Gtek X520-DA2 (2x 10 Gbit/s SFP+) card, and connects to my main switch with a DIGITUS Universal SFP+ DAC cable. I have the same card and cable on my OPNSense firewall machine and they work perfectly. However, on the Proxmox machine I keep having issues. It works (= I power the system on and everything boots and I can connect to it) maybe 40% of the time, the remaining 60% of the time I have to unplug and replug the SFP+ from the switch, and then everything magically works. I've tried adding a script that checks whether the vmbr0 interface has an IP when it boots (it has), a udev rule that takes down and then up again the interface, ... but still nothing. There are days I'd like to simply take the machine out of the rack and throw it around the room. It is more than three months that I have this issue, but I cannot find I way around it.... any tip to where I can seek further ideas to solve it?
Thanks a lot in advance!
Best,
Rob
 
Hi!
are there any errors/warnings visible in the logs? You could also check the difference in driver/kernel output when it works vs when it doesn't. I'd recommend checking with journalctl -b.
 
Hello Gabriel,

Thanks for your reply!
Actually, that's the weird thing, I see nothing strange in the logs...
For instance, this is part of the dmesg for the latest boot:
Bash:
[   21.707181] ixgbe 0000:04:00.0: registered PHC device on enp4s0f0
[   21.884126] ixgbe 0000:04:00.0 enp4s0f0: detected SFP+: 3
[   21.968382] audit: type=1400 audit(1761844066.602:2): apparmor="STATUS" operation="profile_load" profile="unconfined" name="devhelp" pid=1174 comm="apparmor_parser"
[   21.968409] audit: type=1400 audit(1761844066.602:3): apparmor="STATUS" operation="profile_load" profile="unconfined" name="buildah" pid=1165 comm="apparmor_parser"
[   21.968612] audit: type=1400 audit(1761844066.602:4): apparmor="STATUS" operation="profile_load" profile="unconfined" name="epiphany" pid=1176 comm="apparmor_parser"
[   21.968619] audit: type=1400 audit(1761844066.602:5): apparmor="STATUS" operation="profile_load" profile="unconfined" name="cam" pid=1167 comm="apparmor_parser"
[   21.968621] audit: type=1400 audit(1761844066.602:6): apparmor="STATUS" operation="profile_load" profile="unconfined" name="evolution" pid=1177 comm="apparmor_parser"
[   21.968624] audit: type=1400 audit(1761844066.602:7): apparmor="STATUS" operation="profile_load" profile="unconfined" name="vscode" pid=1172 comm="apparmor_parser"
[   21.968626] audit: type=1400 audit(1761844066.602:8): apparmor="STATUS" operation="profile_load" profile="unconfined" name="1password" pid=1156 comm="apparmor_parser"
[   21.968628] audit: type=1400 audit(1761844066.602:9): apparmor="STATUS" operation="profile_load" profile="unconfined" name="Discord" pid=1158 comm="apparmor_parser"
[   21.968671] audit: type=1400 audit(1761844066.602:10): apparmor="STATUS" operation="profile_load" profile="unconfined" name="brave" pid=1164 comm="apparmor_parser"
[   21.968702] audit: type=1400 audit(1761844066.602:11): apparmor="STATUS" operation="profile_load" profile="unconfined" name="QtWebEngineProcess" pid=1160 comm="apparmor_parser"
[   22.125223] ixgbe 0000:04:00.0 enp4s0f0: NIC Link is Up 10 Gbps, Flow Control: RX/TX
[   22.645300] ixgbe 0000:04:00.1: registered PHC device on enp4s0f1
[   22.772866] vmbr0: port 1(enp4s0f0) entered blocking state
[   22.772871] vmbr0: port 1(enp4s0f0) entered disabled state
[   22.772880] ixgbe 0000:04:00.0 enp4s0f0: entered allmulticast mode
[   23.107494] softdog: initialized. soft_noboot=0 soft_margin=60 sec soft_panic=0 (nowayout=0)
[   23.107501] softdog:              soft_reboot_cmd=<not set> soft_active_on_boot=0
[   23.505558] nvme nvme0: using unchecked data buffer
[   25.826751] RPC: Registered named UNIX socket transport module.
[   25.826755] RPC: Registered udp transport module.
[   25.826756] RPC: Registered tcp transport module.
[   25.826757] RPC: Registered tcp-with-tls transport module.
[   25.826757] RPC: Registered tcp NFSv4.1 backchannel transport module.
[   25.829637] vmbr0: port 1(enp4s0f0) entered blocking state
[   25.829644] vmbr0: port 1(enp4s0f0) entered forwarding state
[   25.850754] vmbr1: port 1(eno1) entered blocking state
[   25.850761] vmbr1: port 1(eno1) entered disabled state
[   25.850785] r8169 0000:06:00.0 eno1: entered allmulticast mode
[   25.850865] r8169 0000:06:00.0 eno1: entered promiscuous mode
[   25.927156] Realtek Internal NBASE-T PHY r8169-0-600:00: attached PHY driver (mii_bus:phy_addr=r8169-0-600:00, irq=MAC)
[   26.046487] r8169 0000:06:00.0 eno1: Link is Down
[   26.049483] vmbr1: port 1(eno1) entered blocking state
[   26.049488] vmbr1: port 1(eno1) entered forwarding state
[   26.837270] vmbr1: port 1(eno1) entered disabled state
[   29.842190] r8169 0000:06:00.0 eno1: Link is Up - 2.5Gbps/Full - flow control off
[   29.842218] vmbr1: port 1(eno1) entered blocking state
[   29.842222] vmbr1: port 1(eno1) entered forwarding state
[   31.562832] fbcon: Taking over console
[   31.864158] vfio-pci 0000:01:00.0: resetting
[   31.965410] vfio-pci 0000:01:00.0: reset done
[   32.710596] tap101i0: entered promiscuous mode
[   32.801021] vmbr0: port 2(fwpr101p0) entered blocking state
[   32.801026] vmbr0: port 2(fwpr101p0) entered disabled state
[   32.801042] fwpr101p0: entered allmulticast mode
[   32.801087] fwpr101p0: entered promiscuous mode
[   32.801231] ixgbe 0000:04:00.0 enp4s0f0: entered promiscuous mode
[   35.768758] vmbr0: port 2(fwpr101p0) entered blocking state
[   35.768766] vmbr0: port 2(fwpr101p0) entered forwarding state
[   35.787480] fwbr101i0: port 1(fwln101i0) entered blocking state
[   35.787484] fwbr101i0: port 1(fwln101i0) entered disabled state
[   35.787497] fwln101i0: entered allmulticast mode
[   35.787531] fwln101i0: entered promiscuous mode
[   35.787561] fwbr101i0: port 1(fwln101i0) entered blocking state
[   35.787562] fwbr101i0: port 1(fwln101i0) entered forwarding state
[   35.795351] fwbr101i0: port 2(tap101i0) entered blocking state
[   35.795355] fwbr101i0: port 2(tap101i0) entered disabled state
[   35.795370] tap101i0: entered allmulticast mode
[   35.795420] fwbr101i0: port 2(tap101i0) entered blocking state
[   35.795422] fwbr101i0: port 2(tap101i0) entered forwarding state
[   38.752135] vfio-pci 0000:01:00.0: resetting
[   38.853271] vfio-pci 0000:01:00.0: reset done
[   38.879449] vfio-pci 0000:01:00.1: enabling device (0000 -> 0002)
[   38.929673] vfio-pci 0000:01:00.0: resetting
[   38.929713] vfio-pci 0000:01:00.1: resetting
[   39.109302] vfio-pci 0000:01:00.0: reset done
[   39.109334] vfio-pci 0000:01:00.1: reset done
[   39.110685] vfio-pci 0000:01:00.0: resetting
[   39.213299] vfio-pci 0000:01:00.0: reset done
[   43.511729] tap102i0: entered promiscuous mode
[   43.580093] vmbr0: port 3(fwpr102p0) entered blocking state
[   43.580098] vmbr0: port 3(fwpr102p0) entered disabled state
[   43.580113] fwpr102p0: entered allmulticast mode
[   43.580153] fwpr102p0: entered promiscuous mode
[   43.580312] vmbr0: port 3(fwpr102p0) entered blocking state
[   43.580314] vmbr0: port 3(fwpr102p0) entered forwarding state
[   43.599042] fwbr102i0: port 1(fwln102i0) entered blocking state
[   43.599046] fwbr102i0: port 1(fwln102i0) entered disabled state
[   43.599063] fwln102i0: entered allmulticast mode
[   43.599094] fwln102i0: entered promiscuous mode
[   43.599123] fwbr102i0: port 1(fwln102i0) entered blocking state
[   43.599124] fwbr102i0: port 1(fwln102i0) entered forwarding state
[   43.608194] fwbr102i0: port 2(tap102i0) entered blocking state
[   43.608198] fwbr102i0: port 2(tap102i0) entered disabled state
[   43.608204] tap102i0: entered allmulticast mode
[   43.608246] fwbr102i0: port 2(tap102i0) entered blocking state
[   43.608248] fwbr102i0: port 2(tap102i0) entered forwarding state
[   47.499740] kauditd_printk_skb: 111 callbacks suppressed
[   47.499743] audit: type=1400 audit(1761844092.134:123): apparmor="STATUS" operation="profile_load" profile="/usr/bin/lxc-start" name="lxc-100_</var/lib/lxc>" pid=2102 comm="apparmor_parser"
[   48.092375] vmbr0: port 4(fwpr100p0) entered blocking state
[   48.092383] vmbr0: port 4(fwpr100p0) entered disabled state
[   48.092409] fwpr100p0: entered allmulticast mode
[   48.092474] fwpr100p0: entered promiscuous mode
[   48.092738] vmbr0: port 4(fwpr100p0) entered blocking state
[   48.092742] vmbr0: port 4(fwpr100p0) entered forwarding state
[   48.160160] fwbr100i0: port 1(fwln100i0) entered blocking state
[   48.160167] fwbr100i0: port 1(fwln100i0) entered disabled state
[   48.160193] fwln100i0: entered allmulticast mode
[   48.160251] fwln100i0: entered promiscuous mode
[   48.160311] fwbr100i0: port 1(fwln100i0) entered blocking state
[   48.160315] fwbr100i0: port 1(fwln100i0) entered forwarding state
[   48.169676] fwbr100i0: port 2(veth100i0) entered blocking state
[   48.169680] fwbr100i0: port 2(veth100i0) entered disabled state
[   48.169686] veth100i0: entered allmulticast mode
[   48.169718] veth100i0: entered promiscuous mode
[   48.779863] vmbr1: port 2(fwpr100p1) entered blocking state
[   48.779871] vmbr1: port 2(fwpr100p1) entered disabled state
[   48.779888] fwpr100p1: entered allmulticast mode
[   48.779969] fwpr100p1: entered promiscuous mode
[   48.780151] vmbr1: port 2(fwpr100p1) entered blocking state
[   48.780153] vmbr1: port 2(fwpr100p1) entered forwarding state
[   48.850340] fwbr100i1: port 1(fwln100i1) entered blocking state
[   48.850348] fwbr100i1: port 1(fwln100i1) entered disabled state
[   48.850364] fwln100i1: entered allmulticast mode
[   48.850420] fwln100i1: entered promiscuous mode
[   48.850485] fwbr100i1: port 1(fwln100i1) entered blocking state
[   48.850489] fwbr100i1: port 1(fwln100i1) entered forwarding state
[   48.859164] fwbr100i1: port 2(veth100i1) entered blocking state
[   48.859169] fwbr100i1: port 2(veth100i1) entered disabled state
[   48.859183] veth100i1: entered allmulticast mode
[   48.859214] veth100i1: entered promiscuous mode
[   48.899884] eth0: renamed from veth4eIP3J
[   48.900195] eth1: renamed from vethETuIv2
[   49.269978] fwbr100i0: port 2(veth100i0) entered blocking state
[   49.269984] fwbr100i0: port 2(veth100i0) entered forwarding state
[   49.312788] fwbr100i1: port 2(veth100i1) entered blocking state
[   49.312794] fwbr100i1: port 2(veth100i1) entered forwarding state
[  302.608291] ixgbe 0000:04:00.0 enp4s0f0: NIC Link is Down
[  302.608861] vmbr0: port 1(enp4s0f0) entered disabled state
[  305.261148] ixgbe 0000:04:00.0 enp4s0f0: NIC Link is Up 10 Gbps, Flow Control: RX/TX
[  305.261260] vmbr0: port 1(enp4s0f0) entered blocking state
[  305.261267] vmbr0: port 1(enp4s0f0) entered forwarding state

One can see that enp4s0f0 is up, but still I won't be able to connect to the machine until 305 s (when I get to it, unplug & immediately replug the SFP).
Is there a particular log you think could be of help?
Thanks again!
Best,
Rob