We have a distributed network with more than 30 remote sites connected to each other by a VPN. We would like to control Internet access via proxy servers at each location that contains a local file server. Not all subnets have local file servers. Some locations that are in the same vicinity are on different subnets but are unable to connect to each other. In addition, we have laptop users that move between the different subnets. How can we use Group Policy to manage proxy server settings for certain desktops (and not laptops) within a particular subnet -- for each subnet per computer and not per-user?
Generally, proxy settings will be managed by Group Policy based on computer name or the computer's organizational unit (OU) in Active Directory. This will not solve the problem of transporting the computer from location to location, however, since the computer has not changed within Active Directory.
What you can do, however, is use Group Policy to configure the basic browser proxy settings. For example, you can...
create a computer-based policy to make all proxy settings per-machine rather than per-user. Do this within the Group Policy Object Editor under Computer Configuration > Administrative Templates > Windows Components > Internet Explorer, and then enable the per-computer option.