Changing MTU doesn't stick

[acampbell]

My ISP (Zen) advises tweaking the MTU to improve performance. I can see my MTU set to 1492 in the Advanced WAN profile but when I change it and save the profile it always reverts to 1492. I'm using firmware g, because I don't use Sky and don't want to revert to factory settings unless it's essential.

[billion_fan]

My ISP (Zen) advises tweaking the MTU to improve performance. I can see my MTU set to 1492 in the Advanced WAN profile but when I change it and save the profile it always reverts to 1492. I'm using firmware g, because I don't use Sky and don't want to revert to factory settings unless it's essential.

Once changed hit the 'Edit/Delete' button, then save the profile, and reboot.

[acampbell]

Thanks very much - yes, that fixed it.

[davotoula]

What MTU did Zen recommend pls?

[Tomken]

What MTU did Zen recommend pls?

MTU isn't a one size fits all.

TalkTalk recommend 1432 but TCP Optimizer gave me 1492 and will find the optimum setting for you http://www.speedguide.net/downloads.php

It says no installation necessary but you need to Save it on the download as you need to run the .exe as an administrator after you have set the router and computer's MTU to 1500 and then change them to the recommended setting.

[davotoula]

Thanks a lot for the detailed instructions!

[Tomken]

Thanks a lot for the detailed instructions!

I don't know if you need this, but to manually change the MTU values for the Interfaces in the computer -

(Win 7) - Go Start - type cmd.exe - right click on cmd and select Run as administrator - accept the UAC and enter -

netsh int ipv4 show interfaces

You will be presented with three Interfaces with their Idx No.

1 is the Pseudo Loop Interface and the other two are for the Wireless and LAN which could be say 14 for the Wireless and 12 for the LAN.

The MTU values will probably be default set to 1500, but to change their values either to 1500 or to what TCP Optimizer recommends enter -

In this i.e. I will change the Wireless to 1492

netsh int ipv4 set subinterface 14 mtu=1492 store=persistent

And then do the same using the Index No. for the LAN.

Repeat the ....show interfaces command to confirm the changes.

Enter the command exit to close the command window.