If this does not resolve the issue, proceed to Step #5. If you do, you may need to work with IT to add some exceptions to it. Does the problematic network have a firewall?.
The proxy information you enter should be the same as what is set in the Windows Control Panel under Internet Options > Connections > LAN settings. Next, try opening ArcCatalog and selecting Customize > ArcCatalog Options > Connections, and entering the proxy information there. If it works, then the issue is related to the proxy server. If disabling the proxy server does not resolve the issue, move onto the next step. If yes, work with IT to try temporarily disabling it. Does this problematic network have a proxy server?.If the issue is machine specific (does not happen on other machines on the same network), proceed with Steps #7-9. If the issue is network specific (works on your laptop at home but not in the office), proceed with Steps #3-7. Also, if you are using a laptop, try taking your laptop home for the night and testing the workflow from another network.
On another machine on the same network, test to see if the issue is network or machine specific.