This is the 2860th most frequent French word.
dus
"Dus" is the masculine plural past participle of "devoir," meaning "owed" or "due."
In this case, 'dus' serves as an attributive adjective defining the nature of the delays.
Les retards dus au trafic ont augmenté récemment.
The delays due to traffic have increased recently.
Here, 'dus' is part of the passive verbal structure explaining the reason behind 'ils'.
Ils sont dus à un manque de communication.
They are due to a lack of communication.
Here, 'dus' is a past participle agreeing in gender and number with 'problèmes', referring to the cause of the problems.