Wifi works fine with stock and this rooted version. You might open your TV Box and look if antenna is build in and connected correctly to the Wifi module. This is no software issue and it won't be solved by a firmware update!
There'll be an ICS-update, according to a Chinese seller. But it will take one month or longer to release and I don't know if it's true or they just want to sell more boxes by refering to some update. So, we'll see...