Hello,
I have a weird problem with the DHCP server. There are days where the clients suddenly cannot get an IP address assigned from DHCP, especially those, which were disconnected for some weeks.
An error message in Windows 7 showed that the client cannot find a standard gateway. The router is configured to forward DHCP requests to the DHCP server (OS: Windows Server 2008 R2). When I configured a static IP, the client could be connected to the network. When I changed the NIC to "Get IP-Address Automatically" two hours later, DHCP suddenly works fine. So I do not think that there is a problem with the switch.
It seems that the DHCP service is not working correctly or reacts to requests too late. I read from the internet that the "Task Offload" should be disabled. But I cannot find it in the NIC's properties. Is there another option?