First team manager Jimmy Dean provided his assessment after the Iron suffered a 3-1 loss at King's Lynn Town on Tuesday night, ending a run of five games unbeaten.
Andrew Boyce headed United into the lead but two goals just before half-time put the hosts into the ascendency.
Scunthorpe were on top for the second half but couldn't turn their possession into goals, going down to ten men when substitute Callum Roberts was stretchered off.
The Linnets then broke in the 12th minute of stoppage time to cap their victory with a third.
"I just don't think we showed a good understanding of what it takes to come away and win at a place like this," said Dean.
"The first half was a 'nothing half', in which not a lot happened at all, except a couple of goals from set-pieces and a long range shot went in. They had two shots on target and we had one. We edged the possession but it was all in the defensive third.
"I really don't feel we showed a good appetite for 'the other side' at all, in terms of physicality, winning the first contact, second balls and earning the right to play away from home. That was really disappointing after the run we've been on and the way we played last Tuesday (winning 2-0 at Banbury). We knew it would be hostile and difficult.
"In the first half we weren't good enough but in the second we dominated the game. We had 19 penalty box entries and 42 final third entries. We dominated the possession but they defended the box really well. We then were down to ten men (after Roberts came off) and should have still scored a couple then. Danny Elliott should have taken those two chances - he knows that. We then had the suckerpunch at the end."
He reiterated: "It felt like we went 1-0 up and stopped. We got the goal from the set-piece but didn't capitalise on it - we didn't carry any intensity or fight.
"We came in at half-time having conceded two goals in quick succession and were exactly where they want us - having to come out and chase the game. I'm really not happy with it."
Roberts came off late in the game, but Dean explained the injury wasn't as bad as it looked, as the talented attacker continues looking to get back to full fitness following a spell out.
Dean continued: "It was the sharpest he's looked when he came on. It was a clash of heads, he's got at the front post. We couldn't bandage it up because it was just on his eye. We don't think it was concussion so hopefully he'll be fine, but we'll see how he goes."
United have three games in the space of seven days coming at Glanford Park, starting with the visit of Darlington in the Isuzu FA Trophy second round this Saturday (3pm kick-off).
The message of intent from Dean was simple, saying: "Three home games, we want three wins. We've got to put some momentum back in and can't let this knock us out of our stride. We're in a good place, on and off the pitch now.
"We'll look at where we're at physically because we've had a lot of games in quick succession but the aim is to win, we want a run in the FA Trophy."