Problems with Windows live messenger signing in behind D-Link Router

I recently bought a DI – 524 d-link router. It was easy to configure and works fine. But I am having two issues with it. The first being that Windows Live messenger just wouldnt sign in. I was getting error code 80048820 & 80048439. Port Forwarding doesnt work. What you need to do is go to your routers settings page. Usually 192.168.0.1 and click on WAN settings. Change the MTU value to 1400 and click ok. Now after the router restarts, it should work fine.

The second issue, which I am still working on is extremely slow speed even though I live in an apartment.. Well more on that later!