lag spike in my server

[Gino001]

since a couple of days people experience lag spike on my server idk what to do i tried making a fresh install of the server, reinstalling windows and people still get lag spike from time to time my internet is really good like when im downloading its at 100mb/s + people on my serv dont get high ping neither it just lag every 2 to 5 min or so idk what to do plz tell me u guys expereience something simiar and found a fix