My main home computer is a desktop equipped with an ASUS P7P55D EVO, which comes with two Ethernet network ports; Windows labels them

  • Realtek PCIe GBE Family controller
  • Realtek PCI GBE Famil controller

The only real difference I can observe between the two adapters is the former supports an MTU of 9KB while the latter 7KB.

At home is also a Synology DS413 NAS, connected to the same switch as the desktop. My desktop can only communicate with the NAS via the PCIe (MTU 9KB) adapter.

Why so? Because this adapter is also cranky and can go "disconnected" after a long period of operation; disabling to re-enable does not work as it would either fail to re-enable or the device drops off Windows' list altogether. Rebooting is the only option to revive it. In the meantime, the latter adapter remains operational and other networking activities and Internet access carry on perfectly. Except being able to connect to the NAS - be it the admin web interface or the network share folders. The browser or Windows Explorer just gets stuck loading forever waiting for a response that never comes.

How should I go about troubleshooting this scenario to figure out the cause of the drop in communication via the secondary Ethernet adapter?


The desktop computer also hosts a virtual machine on top of VMWare Workstation. The virtual machine which uses a bridged network connection through that very same network adapter is able to connect up to the web interface and shared folders just fine. Strangeness.

  • Are your two adapters on the SAME network? If so, then you can easily fix this by putting the NAS on a different network and setting each adapter to the different networks. – mdpc Oct 13 '14 at 15:53
  • Yes they are the connected to the same network, same broadcast domain. That is not a problem in itself as I see it. Besides not all computers at home have redundant network adapters so the home only operates one network for all devices. – icelava Oct 13 '14 at 16:18

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