Yahoo Mail and Messenger not working on my DI-704P router…

I’m having a hard time configuring my internet cafe with my router and yahoo mail and messenger. I can’t reply and attach files with yahoo mail… i can’t let others view my webcam. It freezes when i broadcast it. But if i remove the router and just connect the modem to my hub switch, all are just fine… so the problem lies within the router… i’ve tried all port triggering and forwarding but to no avail… can anyone help me?