First to say, I have googled, searched on the Intel website etc, but I couldn´t find anything about this problem, which is kinda weird since I guessed it would be alot of users having the same issue....
Anyway, I have had my ASUS P8Z77 Pro motherboard for about a year, and it has a built-in Intel 82579V NIC.
Last month I upgraded my Internet connection to VDSL to get higher upload, but I didn´t. It was still around 0.5Mbps upstream.
So I checked to see why...
And it seems that the problem is the Intel 82579V NIC driver, which writes a incorrect ip length in the ip header.
When the packet then are to be processed by my firewall appliance, handling my internet connection, it does it healthy checks on the packet. But it dops it, and reports "invalid ip length".
Screenshot from the firewall logs
So started up Wireshark to verify, and it tells the same thing.
So from what I can conclude, this problem is caused by the Intel 82579V driver.
I have tried updated to latest driver from Intel website around four times, uninstall and re-install the driver and NIC two times. But it does not help.
Is this a known problem?
Is there any work around?
Is this a valid behavior, and it is my firewall that causes the problem?
Is there anyone that recognizes these problems?
I have another computer with another motherboard also using the 82579V NIC but have never had any problems on that computer. It is only on this computer I have this issue, regardless of re-installations of Windows or the NIC drivers... same thing, all these packet length errors...