Hi Rhubarb,

I set the MTU to 1500 but the speedguide test still showed that my MTU was 1460 so, as you say, my ISP's equipment must be set to 1460 which, for me, must be the optimum setting.

I also tried the expedient test :

http://help.expedient.com/broadband/mtu_ping_test.shtml

There's something wrong with this test (for me at least). I reduced the packet size down to 1433 but still had fragmented packets. I therefore tried 1432, but then kept getting "Request Timed Out" ! Anything lower than 1432 gave the same result.

No, the Expedient test doesn't work here either. I imagine that it's set up to respond to their customers only. (Assuming you're not an Expedient customer that is.)

Try substituting the www.expedient.net bit for something else:

ping www.draytek.co.uk -f -l xxxx
ping www.bbc.co.uk -f -l xxxx
ping www.speedguide.net -f -l xxxx

all work for me.

Andy

It could be that the router really is referring to MSS rather than MTU, and MSS excludes the TCP header info which takes up 40 bytes:
https://blue-labs.org/howto/mtu-mss.php

Try using an MSS of 1420 instead and see if that helps?

Thank You for the posts.

I've tried several settings and 1460 is definitely the optimum MTU for my line. Anything above 1432 packets (1460 MTU) is fragmented.

Thanks again.

HI, if anyone is struggling with the commands on a rel.3.3.6.2 2710 series Router then try

wan mtu ? (to check MTU value)
wan mtu 1500 (to change value to 1500)
adsl savecfg (to save values to cmos)
adsl reboot (to,,well you get the picture?)

sorry if this is obvious to most but I did struggle

gyroscan wrote: rel.3.3.6.2 2710 series

What is this 3.3.6.2 you speak of?

3.3.5.1 is the latest on the UK site and 3.3.6 is the latest from Taiwan.

Is there a beta firmware kicking about?

Cheers - Andy