Hi There
Did you unplug the box for a few minutes. I had same problem.
I turned off TTbox and unplugged it, I then turned off router and unplugged that for about 5 mins. Restarted router and when that had fully restarted plugged in TT box and restarted it. Then went Y button/ settings/ check for software updates, it loaded a new update (despite saying latest update had been 16/12) and it all worked.