"His personal support to our family during and after the house impeachment proceeding was a gift of kindness we would never forget."

I understand that the prepositional phrase "to our family" is an adjectival prep phrase, but I'm not sure whether "during and after the house impeachment proceeding" prep phrase act as an adjective or adverbial to "His personal support" noun phrase because it answers the question of when; but I also remember that a prepostional phrase after a noun is always an adjective. I'm really curious so please help.