After the sacking of coach Gong Oh-kyun, Dai was serving as CAHN’s interim coach in their V. League match on Dec. 26 when, in the 72nd minute, he rushed on to the pitch to protest referee Nguyen Viet Duan's decision to penalize a CAHN player, used offensive language and threatened the official.
He was shown a red card, but refused to leave the technical area, forcing the game to be stopped so that he could be escorted to the stand.
He then continued to give instructions to the players through his assistant as CAHN went on to beat Binh Duong 3-0.
Two days later the Vietnam Football Federation's Disciplinary Committee announced the five-game ban and a fine of VND20 million.
CAHN were also given a warning for failing to comply with the referee's countdown, resulting in the match kicking off five minutes late.
This was the second time the Hanoi club were fined this season. In their fifth round match, former coach Gong clashed with Nam Dinh FC defender Tran Van Kien during their 2 - 2 draw on Dec. 9.
Le Xuan Hai, another member of CAHN’s coaching staff, who had been banned from the game after receiving three yellow cards, also tried to intervene on the pitch and in the dressing room, and got hit with a VND5 million fine.
The V. League takes a break after an eventful matchweek 8 as the national team plays in the 2023 Asian Cup, and will resume in mid-February.
CAHN are in fifth place with 12 points. Nam Dinh lead with 19 points.
CAHN are said to have reached an agreement with former Thailand national coach Mano Polking to replace Gong from January.