Hi,
Thanks for the reply Barry.

> Check either your m0n0 or the modem to make sure that they are both not
> set to auto detect the speed and duplex of the wan / eth port ..

How can I do this? My modem is a D-Link 300G+. Can I run something on the
monowall box to find out?
 
> This can sometimes cause problems when both devices on the same piece of
> wire are trying to auto detect, I've had it the same as you before,
> works for hours and hours, then dies when it goes quiet ...
> 
> Hope this helps a little 

So do I, thanks :)

Cheers,
Jord