@media (min-width: 992px) {
  .nav-item.dropdown:hover > .dropdown-menu {
    display: block !important;
    opacity: 1 !important;
    visibility: visible !important;
    transform: none !important;
    margin-top: 0 !important;
  }
  /* falls es bei Dir verschachtelte Untermenüs gibt */
  .dropdown-submenu:hover > .dropdown-menu {
    display: block !important;
    top: 0;
    left: 100%;
  }
}