We manage computers for multiple clients. Some of those clients have our network, some have their own.

We have 1 client that is moving to their own network, but we will still manage those machines. Currently, there is a Distribution Server at this site. Once the net network gets switched over, the server will come back to us. 

Will we need to update the clients on the few dozen machines that will remain or will it automatically switch to communicate with the gateway server we have set up?