So I may have stumbled across a fix for disconnects. I have now ran with two teams that I had been having issues with all of last weekend and even early today. I was guiding fireteam members through proper firewall settings, and noticed that one friend had IPv6 enabled yet. Myself and the other person in the fireteam at the time did not. We disabled IPv6 on the last persons PC, and did not have any more disconnects for the rest of the day. I played with a second team and had both members follow the steps to disable IPv6, and we had zero disconnects once again. So, if you havent, make sure your fireteam has IPv6 disable on the proper network adapter. and if you dont know how. here are some steps:
1) Go to control panel
2) Go to Network and Sharing Center
3) Go to Change Adapter Settings
4) Choose Proper Adapter
5) On the Networking tab, scroll down until you see 'Internet Protocol Version 6 (TCP/IPv6) and uncheck the box
6) Press 'Ok'
Also make sure you have all proper UPnP/Port settings configured as suggested by Bungie. This is just my preliminary results, but so far they look promising.
Helped another fireteam with this today that had constant disconnect issues. Looking to be more and more positive. If anyone else has tried this, post your results please!