1492 is standard where PPPoE is involved as PPPoE has an 8 byte overhead. For many routers, this is all they will support, because it's PPPoE.

BTs kit does support mini jumbo frames of 1508, meaning that after the PPPoE overhead, you are left with a 1500 byte MTU. The issue is that your kit at home/the office needs to support this.

1492 is therefore a better blanket recommendation as it is more compatible. But a BT Homehub will work fine at 1500.

AAISP talk about this in their KB here : http://aa.net.uk/kb-broadband-mtu.html

You can ping from a client using various packet sizes to confirm what your MTU can be set to.

ping -f -l 1492 ip_adress

Perhaps I spoke too soon � I was getting 72Mbps last night consistently, on a sync of 75Mbps.

The MTU does seem to make a difference although I haven't exhaustively tested this. With 1488 I seem to eke out around 0.5Mbps faster speeds compared to either 1492 or 1500.

It looks like you really need more speed too....

In reply to a post by epyon:

If you had a perfect line you would sync around 80Mbps.

It used to be shown in the modem as 79999 back when I had such a line. Don't know if that's still the case but after six months my connection speed had dropped to 68Mb/s. Thankfully it's not dropped any further over the last couple of years.

It looks like you really need more speed too....

Well on the homehub i think it just shows in mbps

but yes on my router it says 79999/20000 or something like that i've not checked in a long while.