[plug] users cannot access internet

[Craig Ringer]

> The fact that you cannot ping past the modem is a worry - usually, even if
> the MTU is too big you can still ping your ISP.

When Telstra's broken network is involved, I would find it only a small 
stretch of the imagination to think that an ICMP ECHO could be large 
enough to hit MTU problems. This is, after all, /Telstra/. If it can be 
done wrong....

I do remember having to reduce the MTUs of my client machines and 
gateway when I was (briefly) on Telstra cable years ago. Seemed to 
help... but Telstra solved the problem nicely by trying to rip me off 
shortly afterwards.

Craig