I would start with Tools->Torch:
If that is not sufficient, you may also go to IP->Firewall->Connections:
that should give you enough overview about your WAN connections. From there on, hard to say what you need to do - depends what kind of connections you find
Do you have Queue for you “LAN” users?
It’s because the queues..if you trying to remove dynamic queue Temporarily..and looking for the traffic between Wan and Lan ,You will find it equal
change queue packet 50 to 20000