FTTP - Ethernet Randomly Disconnects

Hi All,

Wonder if someone can help me. This past day or two I have been having serious issues with my ethernet connection disconnecting randomly. It can sometimes happen 5 times an hour maybe only once. If I jump on the Wi-Fi I don't get any disconnections, so the connection is stable it seems to just be ethernet.

Below is an example of the log from my Smart Hub 2, I have gigabit FTTP.

23:54:42, 09 Feb.
DHCP device Connected: 192.168.1.173, 00:d8:61:54:ce:8a, DESKTOP-L2Q683T

23:54:42, 09 Feb.
LAN [ADD] ARP 192.168.1.173 with 00:d8:61:54:ce:8a from br0(eth1)

23:54:42, 09 Feb.
ARP [add] br0(eth1) 192.168.1.173 00:d8:61:54:ce:8a

23:54:37, 09 Feb.
A device connected to Ethernet port 2

23:54:37, 09 Feb.
Wire Lan Port 2 up, Speed 1000 Mbps

23:54:34, 09 Feb.
DHCP device Disconnected: 192.168.1.173, 00:d8:61:54:ce:8a, DESKTOP-L2Q683T

23:54:34, 09 Feb.
A device disconnected from Ethernet port 2

23:54:34, 09 Feb.
Wire Lan Port 2 down, Speed 10 Mbps

23:54:34, 09 Feb.
LAN [DEL] ARP 192.168.1.173 with 00:d8:61:54:ce:8a from br0

23:54:34, 09 Feb.
ARP [del] br0 192.168.1.173 00:d8:61:54:ce:8a

23:52:35, 09 Feb.
SIP Registration - success

23:51:40, 09 Feb.
DHCP device Connected: 192.168.1.173, 00:d8:61:54:ce:8a, DESKTOP-L2Q683T

23:51:39, 09 Feb.
LAN [ADD] ARP 192.168.1.173 with 00:d8:61:54:ce:8a from br0(eth1)

23:51:39, 09 Feb.
ARP [add] br0(eth1) 192.168.1.173 00:d8:61:54:ce:8a

23:51:34, 09 Feb.
A device connected to Ethernet port 2

23:51:34, 09 Feb.
Wire Lan Port 2 up, Speed 1000 Mbps

23:51:31, 09 Feb.
DHCP device Disconnected: 192.168.1.173, 00:d8:61:54:ce:8a, DESKTOP-L2Q683T

23:51:31, 09 Feb.
A device disconnected from Ethernet port 2

23:51:31, 09 Feb.
Wire Lan Port 2 down, Speed 10 Mbps

23:51:31, 09 Feb.
LAN [DEL] ARP 192.168.1.173 with 00:d8:61:54:ce:8a from br0

23:51:31, 09 Feb.
ARP [del] br0 192.168.1.173 00:d8:61:54:ce:8a

Try changing the bits or hardware involved, such as cables and the router maybe even the PC.

Something is up on Ethernet LAN port 2. It’s bouncing around from 1G to 10M connection. It’s not happy.

Restart the SmartHub. Try another end user device and another port on the SH (other than port 2) and see if the behaviour changes.

I have also seen this behaviour and from searching some have mentioned their XBOX One doing this in sleep mode.

My port 1 leads to a switch with many devices attached.


Router Asus RT-AX88u with BT Fibre 900.



I see no impact on any connections other than what is in logs.....

Feb 19 19:46:47 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link DOWN.
Feb 19 19:46:49 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link UP at 10 mbps full duplex
Feb 20 00:54:26 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link DOWN.
Feb 20 00:54:29 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link UP at 1000 mbps full duplex
Feb 20 00:57:10 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link DOWN.
Feb 20 00:57:14 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link UP at 10 mbps full duplex
Feb 20 09:30:40 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link DOWN.
Feb 20 09:30:43 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link UP at 1000 mbps full duplex
Feb 20 09:53:10 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link DOWN.
Feb 20 09:53:12 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9) Link UP at 10 mbps full duplex
Feb 20 12:37:37 kernel: eth2 (Ext switch port: 1) (Logical Port: 9) (phyId: 9)

Are you have to set the port speed to something like '1000baseT full-duplex' rather than 'autoselect'?

And if so does it help?

End user device, especially consoles, laptops etc that show the port link going up and down (in logs) is pretty normal *IF* the end user device is going to sleep or low power mode (or at least the NIC is).

However if the device is awake and active then rapid link up/down is usually not good news.

Plugging another device into the original port and/or moving the original device to another port can give more insight into what is going on.

I got to the bottom of mine, is WAS device sleep!. Took some time to notice the pattern matching the logs.

Yes that’s normal behaviour. The NIC in my laptop dock does exactly the same thing, it actually goes through various phases of putting the network to sleep. The logs on the switch match up precisely with the laptop going into sleep and hibernate.

For a laptop running 1000BaseT NIC they do use a relatively fair amount of energy when operating (wait until you try 10GBaseT!) and if the laptop is out of the box quite conservative (energy star etc) then it will shutdown the NIC at any opportunity to save energy, especially in full sleep mode.

What beats me is that it would be trivial to put a microswitch at the back of the RJ45 port so that when a network cable is plugged in then the laptop can KNOW that there is a cable pulled in and stop turning the device off.

Usually you can disable power saving for the network device, and usually you can tie that to being plugged into the mains.

It wouldn't make any sense to determine whether a device should go to sleep or not based on the presence of a network cable in the port, though. If a network adapter is power saving when the PC is being used then there's a driver fault somewhere, or the OS is mistakenly telling it to go to sleep. This doesn't need extra mechanical devices adding, it just needs the software bug sorting out.