The Terriers crashed to a 4-1 defeat at home to West Ham United on an afternoon when several of their rivals for the drop collected precious points.
Town remain four points clear of third-bottom Stoke City, who are in action tonight at Manchester United.
Wagner’s side travel to the Potteries on Saturday and he is calling for a big improvement on the mistake-ridden display that allowed David Moyes to claim his 200th Premier League victory as a manager.
“We have played 23 games,” said the Town chief. “Usually, it should be enough time for everyone to learn their lesson.
“But even if we say it should be enough time, we did it again against West Ham. It is concentration, as well as the players not realising the danger of the level we are now involved in.
“We have had other moments like this. Swansea away (lost 2-0), we conceded goals like this, against Bournemouth (lost 4-0) we conceded goals like this.
“There were other situations as well. It is not what we like. But, for us it is something that will always be possible as well.
“The players need to realise: ‘Okay, this is danger’. Tommy Smith, before the third one, when he played their player onside, and Joe Lolley for the first goal, didn’t realise the danger early enough. This is what cost them and us. This is part of experience.
“This is not what counts for me now. What counts is how we work with it and how we react. This is what excites me.”
Wagner was particularly annoyed by West Ham’s opening goal, when Joe Lolley was dispossessed on the edge of the home side’s penalty area moments before Mark Noble fired past Jonas Lossl.
Lolley had demanded the ball from his goalkeeper, who would have been much wiser to look elsewhere due to the close proximity of both Noble and Marko Arnautovic.
Lossl seemed equally culpable in that respect but Wagner was adamant Lolley, who later made amends by equalising with his first Premier League goal, was more to blame.
The Town head coach said: “He will learn from it, for sure he will. He showed a reaction with the goal that he scored, and I am pretty sure he will not make a mistake like this one again.
“But, in the end, it cost us because goals change games.”