In an AD domain with Windows Server 2008 R2 DCs users are complaining about delays in the bootup process of the clients. The group policy log reveals that the client is waiting ~ 20-50 seconds for "the network subsystem":
Event 5322, GroupPolicy
Group policy waited for 29687 milliseconds for the network subsystem at computer boot.
This appears to be domain-specific as machines joining a different domain from the same network do not experience any delays and Event 5322 reports <1000 ms wait times at startup. It happens on virtual and physical machines alike, so it does not look like a hardware- or driver-related issue.
Further investigation has shown that the client was taking its time before issuing DHCP requests. In the network traces, I can see IPv6 router solicitations and multicast DNS name registrations as soon as the network driver is loaded and the network connection is reported "up" in the event log (e1cexpress/36). Yet, the DHCPv4 client service seemed to take another 15-50 seconds to start (Dhcp-Client/50036), so the IPv4 address remained unconfigured for a while.
The DHCP client's startup messages in the event log were succeeding the service start of the "Sophos Anti-Virus" service (Sophos Endpoint Security 10.3.7), so I suspected dependencies of the DHCP client service to be the culprit:
But an uninstall of all Sophos components did not remedy the issue. Checking for possible further 3d party drivers which might be messing up, I used NirSoft DriverView, to check for other non-Microsoft drivers and have removed the DameWare remote control and Citrix ICA packages in the result, leaving the system with hardware-related 3rd party drivers only (Intel chipset, network & SATA stuff, Mirage video driver, Macrovision driver).
I also have removed DHCP client's dependency on Tdx - this has led to the Dhcp client service starting significantly earlier, yet the Group Policy is still "waiting for the network subsystem"
Where could I look next?