Secure sites not loading through router - normal sites loading fine - What's up?

[Scuzi]

My mate recently bought a Belkin ADSL modem/router which is set up and working for all normal websites. However, when he tries to access any secure website such as his online banking, the page times out.

How can this be fixed?

The internet connection is provided by AOL and the router is a Belkin F5D9630-4 if that makes any difference.

Thanks

 

[Scuzi]

He needs to reduce the MTU on both his machine and the router to 1400, if he hasn't already.

As far as I know it's simple to change the MTU in the router but how does he change it on the machine? He has 2 laptops connected to it.

After some research, an MTU value of 1400 seems to be recommended. Does this sound about right?