I am struggling to run the Unity 3D behind the proxy. Has any one got any success in doing so. The issue could be due to firewall or zscaler certificates but Unity 3D doesn't provide any way to configure it. I have faced similar situation with Android Studio as well and was able to fix it by adding the zscaler certificates to keystore but this is not the case with Unity 3D.
I kept getting this even on logging in to the unity hub: