IPv4 dropping between Win7 computers - IPv6 fine - Other computers fine

I've been pulling my hair out on this one for a while, and I don't know what else to try, so I'm hopeful that someone here can assist with this strange problem. Sorry for the long post, but it's a strange problem and requires description.

First, my network:

192.168.0.254 Router: 2wire 2701HG-B (DHCP with the router assigning fixed IPs to each box)
192.168.0.100 Desktop7: Win7 Pro
192.168.0.101 Server7: Win7 Pro
192.168.0.102 OtherXP: WinXP Pro

Desktop7 and OtherXP have been playing nice with each other on this network for about a year. Server is a new machine that's causing trouble. Here are its specs: http://support.acer.com/acerpanam/desktop/2010/acer/aspire/AspireR3700/AspireR3700sp2.shtml Specifically, it's using a Realtek PCIe GBE Family Controller for the LAN. I have disabled the wireless. Windows 7 Home Premium came installed, and I upgraded to Professional using the Anytime Upgrade service. There is very little installed on this box.

So, here's the problem in general: when ever I try to transfer any significant amount of data (don't know if it's size or speed that's the culprit) between Desktop7 and Server7, it works for a few seconds, and then neither machine can see the other over IPv4. IPv6, however, works fine. Also, if I try the exact same task from OtherXP to Server7, there are zero problems.

Here's a prime example of the problem: I share a folder on Server7 called "temp ". I open two CMD windows, one constantly pinging Desktop7 using IPv4, the other constantly pinging Desktop7 using IPv6. No issues.

Now, on Desktop7, I open two CMD windows in reverse, one pinging Server7 IPv4, the other IPv6. No problems.

Now, on Desktop7, I open LAN Speed Test (http://www.totusoft.com/), a simple app that transfers files to a share and measures speeds. I give it a 20 MB file to transfer to my temp share on Server7. It works for a few seconds and then ... both IPv4 pings start timing out. Server7 can't see Desktop7. Desktop7 can't see Server7. Both IPv6 pings are fine, and an RDC connection from Desktop7 to Server7 remains active, but the file transfer fails.

This behavior is incredibly consistent and happens at the exact spot each time. I originally noticed it doing a database transfer from mysql instances, and it would fail at the same record each time, as if there's a threshold somewhere that's locking the machines from each other.

After 10 mins or so, the IPv4 pings start working again, and all is good ... until I try another data transfer. I used the Speed Test as an example, but this is repeatable using multiple methods of data transfer.

If I repeat any of these tests between Desktop7 and OtherXP or Server7 and OtherXP, nothing goes wrong. All works as expected. It is just between the two Windows 7 Professional machines.

Server7 has Windows Firewall disabled and no additional firewall software installed. I see nothing in the Event log referencing this. I have no logs on my Router, but there's nothing I can see in the config that would be making this happen.

Desktop7 does have ESET Smart Security 4 firewall on it, but it's not restricting anything to Server7, and I've disabled the firewall when running these tests.

I don't know what's happening as I'm not an experienced networker, but the "feel" is like some transfer threshold is hit, and the two machines are denied access to each other for 10 mins by a designed timeout or an error-clearing timeout.

Again, sorry for all the words here, but I wanted to describe the problem completely. I would be very grateful if anyone here could assist me in resolving this.

Thank you!!!

 

Welcome aboard.

Have you tried updating Realtek LAN driver on server ?

If you are not using IPv6, disable it & check for the problem.

 

Thank you for the suggestions. I have indeed tried updating the driver, but it says I have the latest: 7.17.304.2010

I have also disabled IPv6 on one and then both computers with no success.

Finally, I've tried all kinds of different settings in the Advanced properties of my controller, and haven't found a magic combination. Here's what I have in the list.

ARP Offload: Enabled
Auto Disable Gigabit: Disabled
Energy Efficient Ethernet: Disabled
Flow Control: Enabled (think I've tested disabling this)
Green Ethernet: Enabled
Interrupt Moderation: Enabled
IPv4 Checksum Offload: Rx & Tx Enabled
Jumbo Frame: Disabled (think I've tested enabling this)
Large Send Offload v2 (IPv4): Enabled
Large Send Offload v2 (IPv6): Enabled
Network Address: Not Present
NS Offload: Enabled
Priority & VLAN: Priority & VLAN Enabled
Receive Buffers: 512
Receive Side Scaling: Enabled
Shutdown Wake-On-Lan: Enabled
Speed & Duplex: 1Gbps Full Duplex (had it on Auto Negotiation when problem started)
TCP Checksum Offload (IPv4): Rx & Tx Enabled
TCP Checksum Offlaod (IPv6): Rx & Tx Enabled
Transmit Buffers: 128
UDP Checksum Offload (IPv4): Rx & Tx Enabled
UDP Checksum Offload (IPv6): Rx & Tx Enabled
Wake on Magic Packet: Enabled
Wake on pattern match: Enabled
WOL & Shutdown Link Speed: 10 Mbps First

 

Are you on a 1 Gbps network ?

 

I am. Desktop7 has different configuration settings, but it does have a Speed & Duplex option that is set to Auto Negotiation and indicates it has decided on 1Gbps. Also, all machines are connected to a Netgear GS108 gigabit switch, which is then connected to the router (that connects to the ADSL).

This setting looked suspicious to me: WOL & Shutdown Link Speed: 10 Mbps First. So I changed it to 100 Mbps. It does not appear to have helped.

 

Your switch supports Jumbo frames.

Disable Jumbo frames from all your computers & switch as this can also cause problems.

edit: Ok scratch that advise about disabling jumbo frames on switch as you can't - it being a non managed dumb switch.

 

It won't as it only applies when you wake up your computer through WOL.

 

Jumbo frames are disabled on Server7. I don't see an option in config to disable them on Desktop7, and I don't know how to access my switch. On that note, no option for jumbo frames on my router either.

 

Of note, I tried setting Server7 to 10Mbs half duplex to see if it's a high-speed issue, but the problem remains.