Set the time keeper role or bad cop
In every meeting there should be a bad cop.
That's the person who has a timer and let's everybody know that we already used half the time we allocated for that topic. That's the person who says: "Hey people, we have three minutes left for this topic, so let's summarize!" That's the person who says: "So, last minute: here is the summary, and sorry Bob, that detail doesn't matter for now, we'll discuss that at another time".
Being the time keeper can be a bit hard. So if it's the first time you do it, put a timer on your laptop. By doing so everybody can see that there isn't so much time after all. And if you are a bit shy, you can just point to the timer as a polite reminder.