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Jumbo Frames enabled slows 209+ to a crawl.

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Can anyone please help me to solve a puzzle I have discovered,
when testing my 209+ ?

I have a 209+ with a single 1.5TB Seagate drive connected to a
Netgear GS108T (with JF enabled), which in turn is connected to a
laptop with a PCIe gigabit NIC.

During upload testing to the NAS, without Jumbo Frames, enabled I measure a
consistent 28MB/s. The excellent reviews here (minor brown nosing, but never the less true) indicated there may be some more horsepower to be had by such a setup so I have experimented with JF.

To begin with I set both NAS and laptop to 4K, tested with the ping options
to ensure the packets are not begin segmented and then ran tests.
The upload performance went from 28MB/s to 3MB/s.

And any combination of JF sizes sees no change in upload speed.
It's about 10 times slower. However as soon as I switch Jumbo Frames off
on the Synology NAS performance returns to about 28MB/s.

Am I failing to set something up correctly? Or is there any check list I can reference to see where the bottleneck is forming ??

Any help gratefully received.
I have seen jumbo frames not improve performance. But not so negatively affect it.

Can you try a filecopy to another computer with a gigabit NIC that supports jumbo frames to see if the issue is specific to the 209+?
thanks for your reply - I've had a little time now to test the issue against a number of other machines. Lucky enough it looks like I found a fair comparison from which to do some testing.
To explain, my laptop (running windows Vista [32bit]) has a Marvell Yukon PCIe NIC [88E8055] and my wife's iMAC has a Marvell Yukon PCIe NIC [88E8053]. I tested the file upload/download from her iMAC with various size jumbo frames enabled and found that the symptom I'd seen (3 MB/s from 28) did NOT appear. In fact at 4K frame size performance lifted slightly (+ 2/3 MB/s).
So, I have updated the driver on the laptop to the latest version []
and this has fixed the issue. I now get approx 43 MB/s upload and 50+ MB/s download when moving files of approx 1GB with 4K jumbo frame setting on both the NAS and laptop.

regards! :)
Thanks for posting the update. Glad you got it fixed.

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