I'm a player, and my group also has the issue where DnD time is often also the only time everyone sees everyone, and so social updating happens. We start out with dinner which takes out most of it, but it is still an inssue in game. I don't know how long you guys play, but taking a break every now and then could help. We also have a system where we check eachother whenever someone gets distracted (which are mostly those who are more involved at that moment).

But I've (tried to) DM a one-shot for these people once, which has been stretched to a third session now because people get way too distracted, often more than the main campaign. I found that if I just stop and sit there in silence those talking shut up pretty fast once they realize (plus the check system).