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Standard User willdobbo
(newbie) Tue 09-Feb-21 23:55:39
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FTTP - Ethernet Randomly Disconnects


[link to this post]
 
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
Standard User Michael_Chare
(fountain of knowledge) Wed 10-Feb-21 00:20:13
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Re: FTTP - Ethernet Randomly Disconnects


[re: willdobbo] [link to this post]
 
Try changing the bits or hardware involved, such as cables and the router maybe even the PC.

Michael Chare
Standard User Pheasant
(committed) Sat 13-Feb-21 09:50:46
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Re: FTTP - Ethernet Randomly Disconnects


[re: willdobbo] [link to this post]
 
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.

My Broadband Speed Test


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Standard User woooshuk
(committed) Sat 20-Feb-21 15:27:22
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Re: FTTP - Ethernet Randomly Disconnects


[re: Michael_Chare] [link to this post]
 
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)
Standard User Michael_Chare
(fountain of knowledge) Sat 20-Feb-21 16:23:38
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Re: FTTP - Ethernet Randomly Disconnects


[re: woooshuk] [link to this post]
 
Are you have to set the port speed to something like '1000baseT full-duplex' rather than 'autoselect'?

And if so does it help?

Michael Chare
Standard User Pheasant
(committed) Sat 20-Feb-21 17:35:14
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Re: FTTP - Ethernet Randomly Disconnects


[re: woooshuk] [link to this post]
 
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.

My Broadband Speed Test
Standard User woooshuk
(committed) Sat 27-Feb-21 23:57:01
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Re: FTTP - Ethernet Randomly Disconnects


[re: Pheasant] [link to this post]
 
I got to the bottom of mine, is WAS device sleep!. Took some time to notice the pattern matching the logs.
Standard User Pheasant
(experienced) Sun 28-Feb-21 08:16:25
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Re: FTTP - Ethernet Randomly Disconnects


[re: woooshuk] [link to this post]
 
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.

My Broadband Speed Test
Standard User jabuzzard
(experienced) Sun 28-Feb-21 12:51:28
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Re: FTTP - Ethernet Randomly Disconnects


[re: Pheasant] [link to this post]
 
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.
Standard User jpm
(member) Sun 28-Feb-21 13:11:35
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Re: FTTP - Ethernet Randomly Disconnects


[re: jabuzzard] [link to this post]
 
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.
Standard User aidanh
(newbie) Sun 28-Feb-21 13:35:41
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Re: FTTP - Ethernet Randomly Disconnects


[re: jpm] [link to this post]
 
It depends what you're using the device for. If you're doing actual networking but not physically sat at the laptop using the device, moving the mouse, etc I can imagine this would trip the power saving even though you probably don't want this to happen until the network transfer is over. Also if you want to wake the device via Wake-on-LAN, again power saving is undesirable. These are edge cases though, the way most people use their devices they won't be impacted by the power saving.
Standard User clyde123
(member) Mon 01-Mar-21 09:04:51
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Re: FTTP - Ethernet Randomly Disconnects


[re: aidanh] [link to this post]
 
This is something I have been routinely looking at on every laptop and PC that comes my way for a few years now.
Check the properties of the network card, and ensure that under Power Management, that the "Allow the computer to turn off this network card to save power" is NOT checked.
It's just one more thing that can - very occasionally - cause unexpected behaviour. Which can waste enormous amounts of time to fix.
Standard User Pheasant
(experienced) Mon 01-Mar-21 19:01:52
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Re: FTTP - Ethernet Randomly Disconnects


[re: clyde123] [link to this post]
 
Yes it drives me batty too. I think manufactures do this to keep their "green credential" accountants happy, and to save every last milliwatt, but for the most part in practice, it's a pain in backside.

My Broadband Speed Test
Standard User ian72
(eat-sleep-adslguide) Tue 02-Mar-21 09:47:25
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Re: FTTP - Ethernet Randomly Disconnects


[re: Pheasant] [link to this post]
 
I'm guessing they have to do it in order to meet rules laid down by EU/US/UK for energy efficiency. It is like the Sky boxes that have to go into deep sleep when turned off in order to meet the rules but most people turn it off so that they start up more quickly.
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