Ah ok, hmm maybe I'll give it a shot sometime then. It seemed kinda odd since I don't really remember the games having much that ties it together beyond the setting. I've always sorta kicked them off as a new game rather than a sequel/prequel etc
Fallout 1/2/NV all have direct links to one another and show the development of California and Nevada over a 100+ years.
Fallout 3 and 4 are more distinct from 1/2/NV because of location but they have their own links to one another. One of the major plot elements and factions of Fallout 4, replicants and the Institute, first appeared in one of the major sidequests in Fallout 3. And the BoS factions in Fallout 3 and 4 are linked.
It's all designed to easily standalone but the links are there for those who are interested.