We have a client that runs a Windows Server 2012 Std for 30 PCs/Laptops.
The are running (new) Netgear Gigabyte switches and BT Business Hub (soon to change to Draytek)
Over the last week or so the users have mentioned it can take 10 minutes to just log on to their PC's, they aren't even using roaming profiles.
The DHCP and DNS is setup on the Server so all the client's PCs are points to the servers IP address as their primary DNS (192.168.1.2) and the Servers DNS settings are the same. However under the Forwarders tab in DNS settings we have opendns and google
Spec of the Server
Server: HP Proliant DL380p Gen8
Processor: Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz
Memory: 40.0 GB
The client machines are all Windows 7 Pro.