Some network administrators require you to connect to internal or external network resources via a proxy server. By default, the Wi-Fi networks are not configured to connect via a proxy, but you can use the following steps to change that for each Wi-Fi network you’ve added.
1) Touch and hold a network with connected status in the list of Wi-Fi networks.
2) Touch “Modify network” in the dialog that opens.
3) Select “Advanced options”.
4) If the network has no proxy settings, touch “None” under “Proxy”, then touch “Manual” in the pop-up menu.
5) Type the proxy settings supplied by your network administrator.
6) Finally, touch “Save”.
Note: all of the above steps only change the current Wi-Fi setting. To change the proxy setting for others, you should modify them individually.