Lag and dc´s when joining to a party

This problem start like 1 week ago, before that everything goes well with the game no lag, no dc´s in solo or in a party. Now when im solo i have no problems, but as soon I join to a party i get laggy and get dc, even if im in my own instance, so i think that is not a gateway problem, but im not an expert i already run a PingPlotter and send my info to support@grindinggear.com. Thanks for your time.