In customer environments that use a proxy server to control internet access, it may be required that the systems be configured with the network proxy settings at a system level. 

This can be done by following the steps below;

Download a copy of PSEXEC from the link below;

https://docs.microsoft.com/en-us/sysinternals/downloads/psexec

Unzip the copy of PSEXE and run the following command from an elevated command prompt;

PSEXEX -d -i CMD

This will launch a command prompt running under the system context, in the command prompt enter in the following command;

C:\Program Files\Internet Explorer\iexplore.exe

This will launch Internet Explorer.

In the Internet Explorer Window, you can now configure your proxy settings based on the requirements for your proxy server to function