Speedtouch TG585v7 vs DG834 v3

[#1]

I got sent the new speedtouch router as i plan on staying with PN for a longish time  . overall is a very good router but i have had to revert back to my netgear 834 because of the MTU settings.
For a while i have been getting very bad lag whilst playing games online mainly Quakeworld , i have tweaked my MTU and rwin 1468 MTU and RWIN 36868 , but i was still laggin and getting PL along the hops to servers averaging around 30 - 50 % . I remembered that the netgear had this setting in the GUI to set the MTU so i thought i would hook it up again , now after setting 1468MTU in the netgear i have no PL and no lag what so ever  .My question is how can i hack the speedtouch to set the MTU as i don't like the 834 .

[#2]

You need to do it through the CLI (Command Line Interface) and the command looks like this  {admin}=>ip ifconfig intf=Internet mtu=1500 where 1500 is where you put the value you want to use
This assumes it is the same as the 585v6
This is a link to the v6 CLI manual http://www.maxdsl.md/cti/modems/st585v6/st585v6_cli.pdf