NAS randomly unaccessible

[gurth]

I've installed FreeNAS on D525MW Intel board.

From time to time, during the whole day, NAS is randomly unaccessible. It doesn't matter, how many clients are connected.

I've tried:

• change Gbit switch
• change onboard NIC (now, there is some intel PCI)
• change cable
• add some tunning parameters to sysctl.conf (from freebsd website)
• change NIC parameters on clients (windows 7/Vista/XP)

There are only CIFS and SSH services enabled, RAID 1 ZFS.

Detailed description:
I work with smb shares, large files are copied at 70MB/s. After some time of "doing nothing" with network is share unaccessible. So I try ping to NAS and there is no response. But another clients have full access at full speed. Net is fully accessible from NAS.

What (sometimes) helps:

• disable/enable my NIC
• change "some settings" on my NIC (I know, funny :) )
• do nothing and wait

If problems could be only on my PC, that would be great. But this symptoms are migrating from one PC to another totally randomly...

Do you have any idea, where could be the problem?

I am trying to solve this 3rd day and I am going to be desperate :)