Thanks for those. The second link is how I carried out the fragmentation test. The first link is interesting cos the screenshots (albeit for a different model of TP-Link router) show a default MTU of 1500, rather than 1480 (the default for my TP-Link router). Maybe a firmware update would change this but TBH, performance is more than acceptable with an MTU of 1492 so I'm not particularly worried. Also

"Is there anywhere on Coms site that states what settings we should use for our modems?"

As mentioned above, I originally raised a ticket directly with Coms support and got a reply from a "senior network analyst" stating that they recommend a value of 1492. So that's what I'm using.

I use 1500 mtu on my speedtouch 585 v6

1500 (1472 + 28 for header) checks out OK here. Maybe 1492 is being suggested to allow an 8 byte safety margin.

In reply to a post by My_brain_hurts:

Is there anywhere on Coms site that states what settings we should use for our modems?

I dunno! I was the one telling you Commies the correct values and how to find it.

There's an important omission from your 2nd link. Before carrying out said tests you must ensure that MTU is not restricted to under 1500 anywhere in your system, router, PC, or OS.

Edited by XRaySpeX (Tue 25-Feb-14 13:08:21)

Sorry, my bad. I was asking about the list of modem settings not just MTU. I've started a new thread on it as I think maybe there are a few peeps out there who could use the gen to check their modems are correctly set up.