Ethernet connection disconnects randomly

User Support
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1

Hi! Since recently, my ethernet connection disconnects randomly and reconnects automatically after some time. I’m on Qubes release 4.1.2 (R4.1). I use debian-based disposable net-vms including sys-net.

In sys-net:
sudo dmesg | grep -v audit
[ 6348.388192] e1000e 0000:00:05.0 ens5: NIC Link is Down
[ 6352.003762] e1000e 0000:00:05.0 ens5: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
[ 6354.417692] e1000e 0000:00:05.0 ens5: NIC Link is Down
[ 6358.357893] e1000e 0000:00:05.0 ens5: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
[ 6361.367944] e1000e 0000:00:05.0 ens5: NIC Link is Down
[ 6364.294441] e1000e 0000:00:05.0 ens5: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
[ 6484.521943] e1000e 0000:00:05.0 ens5: NIC Link is Down
[ 6488.511884] e1000e 0000:00:05.0 ens5: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
[ 6578.500432] e1000e 0000:00:05.0 ens5: NIC Link is Down
[ 6582.324698] e1000e 0000:00:05.0 ens5: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
[ 6587.764212] e1000e 0000:00:05.0 ens5: NIC Link is Down
[ 6591.529139] e1000e 0000:00:05.0 ens5: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None

lspci
00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II]
00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
00:02.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device (rev 01)
00:03.0 VGA compatible controller: Device 1234:1111 (rev 02)
00:04.0 USB controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2 EHCI Controller (rev 10)
00:05.0 Ethernet controller: Intel Corporation Ethernet Connection (5) I219-LM

I’ve tried qvm-prefs sys-net kernelopts ‘pci=nomsi’ (in dom0) but it didn’t solve the problem (although the problem might occur slightly less often now, but it’s hard to tell because it’s so random).

Do you have any idea what the problem could be? The ethernet cable itself is fine, I verified with a cable tester.

Thanks!

2

Did you try to use Fedora for sys-net, as a test?

3

Thanks for the idea! :slight_smile:
I haven’t tried this yet because I don’t have the fedora template installed.
I’ll try and report later.

Btw. I found a workaround using a small gigabit switch:
Before, does not work:
Switch <-- long ethernet cable --> qubes
After, works fine:
Switch <-- long ethernet cable -- small gigabit switch --> qubes

4

Possibly related: I’ve noted, lately, that sometimes my sys-net-wifi just stops working and I have to restart it. However…it’s connecting to wifi, not ethernet.

Edit to add: It still shows as connected; it just has no throughput.