Mmmm, I dunno if the Great War is a good reason for Portugal losing its colonies. Since Portugese colonial troops had their own front against the German colonies and thus would've been reinforced and helped by mainland Portugal during the war. Which would've made later uprisings for independence pretty difficult since there would've been a lot of not only colonial troops, but Portuguese Army and Naval forces too.

Their Indonesian colonies were most likely taken over by the Empire of Japan though, no doubt there.