Marco Silva expressed his ‘frustration’ at Everton’s defensive woes in their 3-1 defeat at Bournemouth on Sunday.
Bournemouth went ahead through Callum Wilson from a set-piece, before Dominic Calvert-Lewin levelled for Everton.
But Ryan Fraser’s free-kick and Wilson’s second goal of the afternoon condemned the visitors.
Silva told talkSPORT: “It’s a big frustration for us, a big frustration because it’s not something you do just one day during the week, it’s something that’s part of our weekly plan.
“We took some time to settle and address everything last season, but after we addressed it, we went so many games without conceding goals and giving so easy things to our opponent.
“We came here and conceded again. Like I said it’s better to be aggressive and active and challenge that moment. It’s a big frustration.
“We know what our opponent does, we were prepared, but we came here and didn’t do enough.”
Everton’s next league away game is at Burnley on October 5.
And their away form could harm their chances of breaking into the top six this season.
Silva added: “For us as a club, it’s not good enough, we have to show more strong character and personality, as well, and we have to be more solid.
“We’ll improve our away form, I have no doubts about that. We should and will improve.
“It’s up to us to work hard, to keep working really hard, to settle and address everything that we need.”