Sony Xperia Tablet Z can't setup proxy When I'm on my tablet, I go to my wifi network, tap and hold on it, and I get a popup menu. I hit modify network, and get a popup for the wifi.

I tap "show advanced options", and then change Proxy Settings from None -> Manual.

The moment I do this the Save button grays out, and I can't click it.

Even if I fill in the proxy hostname and port, the save button remains grayed out.

Do I need root? Sorry if this is fairly obvious, I just found nothing online.
I think you missed the password. Fill Password, then enable proxy to manual then type the proxy hostname and then the port. The all three need to be filled for the connect button to be enabled.