How to change MTU of FC2?

[serverxeon 0]

im trying to use my windows xp as a gateway for my FC2 to connect to the internet.

 

However, im using a PPPoE on the xp. Thus having the MTU problem

i need to reduce MTU from 1500 to 1492. anyone knows how?

 

The situation now is, i am able to access localhost of my windows system. but not able to access external website. (most of them are inaccessible)