I was driving earlier when i noticed smoke coming from engine, pull over and check and see my coolant flange was spraying coolant and so i added coolant and patched it kinda just to drive it home like 1.5 miles, and it was shifting fine and i pull over to let temp cool down a bit although i was like .5 miles away at this point and didnt wanna overheat since it was getting close then go to go again and it was good then going from 2nd to 3rd it just started coasting as if in neutral so i stopped and tried all gears 1-6 and R and all nothing it revs up and all but goes no where like in neutral and got it home and realized i can switch gears on and off without touching clutch, what could cause this?

 

And its a 2002 Audi TT Quattro AWD 1.8T