Question Fibre connection exposing problems with home networking (Devolo/Ethernet General Failure/Packet loss) ?

Otiggen

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Oct 30, 2015
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This is part documentation of what I discovered, and part what I am still working on.
I recently got fibre to the home (Community Fibre) in the UK and I am using it with my old Dell E6420 Latitude.
I am only subscribing to the 300Mbps service as that should be sufficient for my needs.
The provided router was a Linksys VELOP

Using WiFi I was getting good speeds but there seemed to be some buffer bloat with the data rate rising and falling periodically.
As I had a Devolo 1200+, and this house is small, I decided to try connecting by Ethernet.
There is a single Ethernet out on the Linksys VELOP. It runs into a Devolo 1200+, and from there, via Powerline, to the Devolo 1200+ WiFi ac.
Devolo Cockpit shows inter-Devolo speeds well above the fibre rate. e.g. 500/800 Mbps.

First I tried the Devolo WiFi connection - and got better speeds than direct from the VELOP. The distance is shorter, but even when I move around the house the speed seems more consistent. But being a speed freak and knowing a gaming son will come around soon and bug me about lag times... I decided to try an Ethernet connection from Devolo to laptop.
The connection came up at 1Gbps with very good ping times (mostly 1-2ms). DSLreports speed test showed me reaching over 250 Mbps up and down on the graph (the numerical values displayed were over 300 Mbps)... but I was suffering erratic behaviour when browsing.

So when I pinged the VELOP from the laptop I was getting regular "General Failure" messages every 10 seconds:

Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
General failure.
General failure.
General failure.
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
General failure.
General failure.
General failure.
Reply from 192.168.1.57: bytes=32 time=1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64
Reply from 192.168.1.57: bytes=32 time<1ms TTL=64


it looked like the link speed was being re-negotiated every 10 seconds.
The Dell E6420 Ethernet card is a Intel(R) 82579LM Gigabit Network Connection

As a test - I tried connecting directly to the VELOP (no Devolo) and I did not see this issue.

After a lot of experimentation (including a newer shorter cat5e cable which didn't help), I found I could get rid of this problem with these steps:
1. Install latest driver from the Intel site: "Network Adapter drivers release 25.0 (the last version that supports Windows 7 - as that is what I am running) [seems to identify itself in Device Manager as Intel 29/03/2016 12.15.31.4]
I installed it by unzipping the package and manually browsing to get the driver from Intel Components\PRO1000\Winx64\NDIS62
[Windows update would like to revert me to an earlier driver - this one is also later than any Dell provide for this laptop]

2. In the Advanced Properties - force this Ethernet adapter to be a Master.

Now that was a pretty good result - but what I was left with was intermittent timeout errors on the ping commands totalling 6-9% packet loss... so still not perfect.
I have done a lot more experimentation and reading.
Under Linux I believe some people have disabled K1 power save mode and that might be a resolution but I can't see how to do that under Windows.
I also wonder whether the Intel AMT could be playing a role - I have disabled it as much as I can but as it shares the Ethernet with the main cpu I can see it might have the potential to be getting up to some mischief... though I have no idea how to address that if it is.

Today I started playing around more with the Advanced parameters of the Ethernet adapter in Device Manager... and I thought I had solved the problem... until I realized that the link had now dropped to 100 Mbps.

So my current problem is that the speed of the link will no longer operate at 1Gbps between the laptop and the Devolo. Diagnostics on the laptop say
"Link speed: 100Mbps. The link partner is not capable of higher speeds. "
I tried unplugging the Devolo and reconnecting it, unplugging the Ethernet cable and reconnecting, changing to a different Ethernet cable, overriding the MAC address of the Ethernet card (in case the Devolo has decided to 'black list' it. All to no avail. I guess a reboot of the laptop is my next option.
 

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