Macbook Pro WiFi Painfully Slow on Corporate Network, PC Works Fine
Try this setting, it helped me in the same situation :) In the network settings change the address of DNS servers to Google's ones: 8.8.8.8 or 8.8.4.4

For this go to Settings &gt; Network &gt; Advanced... &gt; DNS > press + and enter DNS address.



Or, vice versa, you may ask your system administrator for any specific DNS and probably proxy settings that your company might have due to security reasons and then enter them in the Proxy tab.