It may not help but is the date/time correct?
We cover a lot of odd network issues over in the CNET Networking Forum and I'd check this as well as put the TV into the router's DMZ entry.
I got TV mid Dec 2012,Subscribed to HBO early Jan 2013 thru Time Warner.App worked great for 3 weeks then not working.Spins forever on "connecting". I have deleted and reinstalled several times. Once or twice I got a message while it was trying to update HBO GO "network is not connected" - but all other apps work fine... so the network is ok. I contacted HBO GO and they suggested first) uninstall HBO GO then restoring Smart Hub to default settings - then reinstall HBO GO. It still did not work. Would it help to download the app to a USB thumb drive and try to install direct to TV and not over the internet? I love the HBO GO app! HELP!
My smart hub version is 4.5311-5.0
My firmware version is -T-MST10PAUSC-1025.0 date 2012-12-05.