Recently back from a hamstring injury, the midfielder scored all three goals in the second half, including an assist from fellow Spurs loanee Alex Pritchard.
Ryan made it 3-0 a minute into the second half, a low finish from a pass from another ex-Spur, Yaser Kasim. He then slotted home from the penalty spot for 4-0 before flicking home Alex's cross.
And there was still time for Ryan miss a penalty in the final minute!
Ryan, Alex and Grant Hall all completed the 90 minutes as the Robins moved up to 10th.
Jake Livermore started as Hull impressed despite a 2-0 defeat against Manchester City in the Premier League on Saturday.
In the Championship, Adam Smith came on for the second half of Derby's 3-0 home defeat against Burnley. The Rams were 2-0 down at the break.
Bongani Khumalo played 90 minutes as Doncaster were beaten 1-0 at home by Bournemouth.
Yago Falque's debut in La Liga for Rayo Vallecano sadly only lasted five minutes as he suffered a muscle injury. Levante ran out 2-1 winners of that game.