We have a client who has a Server 2012 domain running 3 server on Hyper-V. One server is running as DC, DNS, DHCP. Other is Exchange 2013 server. The 3rd is a voip system. The issue is with internet browsing which unacceptably slow on domain workstations.
Tested a computer directly connected through internet no issues.
There current internet is Fibre 100Mbps/50Mbps.
The firewall is Sonicwall TZ105W.
When a machine not part of the domain is connected to the network browsing works fine while using the internal DNS. But once you join this machine to the domain problem starts.
I have hit a brick wall. Any suggestions would be great. I have tried to setup DNS forwarders to the ISP didn't make any difference.