[2] In 2018, Syihan joined Negeri Sembilan but was banned for 20 months by Asian Football Confederation for failing a doping test while participating in the AFC U-23 Championship in China.

[3] In 2020, Syihan returned from suspension and signed for Petaling Jaya City Due to a lack playing time because of the in-form current goalkeeper, Kalamullah Al-Hafiz, he left the club for another stint at Negeri Sembilan.

Syihan made an unofficial appearance for Malaysia at the age of 17 years 1 month 4 days in a charity match (non FIFA 'A' international) against Palestine after replacing Norazlan Razali.

Syihan made his official senior team debut on 16 April 2022 during the 2023 AFC Asian Cup qualification final fixture against Bangladesh.

He was also a member of the nation's squads at the 2022 AFF Championship and the 2023 AFC Asian Cup where he was notably famous among the South Korean fans.