The Bees won 1-0 at London stadium thanks to Kevin Schade's strike.
Potter later said, "I think the second half response was really, really positive but I think we have to be honest and say the first half wasn't what we wanted at all.
"Sometimes that happens, especially when you concede an early goal. We suffered a little bit. I think they played well. They did what they did well. We were too unstable for our liking, but I think we'll learn a lot from that.
"The second half was really positive. I thought Evan (Ferguson) came on and did well. James (Ward-Prowse) showed his quality. Ollie (Scarles) had an impact. We pushed and pushed.
"If we're going to lose a game, I'd rather lose it in the second half the way we played than the way we played in the first half, because it's nowhere near what we want to be. But, as I said, sometimes on the journey you have to have a little step back to go forward again. That's what we'll have to focus on.
"Like I said, the positives were there, there is learning that we have to do and try to improve.
"The first half, there wasn't too much going right for us, if we've been honest.
"Sometimes you have to just say, look, we didn't do what we wanted to do and it's a collective. It's not just the players, it's myself, and everybody involved.
"So you have those times sometimes, when you go down early, it can change the dynamic a little bit."
He also said, "I understand the supporters' frustration.
"We were all frustrated at half-time for sure. We have to be honest with that, there's no point in saying anything else.
"We weren't at the level we want to be and the only thing we can do is learn from that and make sure it doesn't happen again, essentially.
"Like I said, the response from the players was really positive, really good. We feel that we're making progress, but sometimes when you have a performance like we did in the first half, it's a little bit of a step back, but I think sometimes you need those to be able to go forward as well. As I said, we'll learn a lot from the game.
"The support's been brilliant, we can't complain about that at all. They're well within their rights to be disappointed at half-time, absolutely. But the second half, the response of the crowd was first class, it was brilliant and they got behind the team, so that's all we can ask for."