MTU setting not changing.

[jefa111]

charter cable, 2000/256, xp home

I'm using the SG tcp/ip optimizer and it shows that the maxMTU is 1500 but after I apply, reboot, and run the SG tcp/ip analyzer i get this:

MTU = 1440
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput.
MSS = 1400
MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

Default Receive Window (RWIN) = 64240
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 64240

For optimum performance, consider changing RWIN to a multiple of MSS.
Other values for RWIN that might work well with your current MTU/MSS:
515200 (MSS x 46 * scale factor of 8)
257600 (MSS x 46 * scale factor of 4)
128800 (MSS x 46 * scale factor of 2)
64400 (MSS x 46)
bandwidth * delay product:

Your RcvWindow limits you to: 2569.6 kbps (321.2 KBytes/s) @ 200ms
Your RcvWindow limits you to: 1027.84 kbps (128.48 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 32 hops

TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000

Any thoughts are much appreciated.

[mccoffee]

Are you behind a router at all??


http://www.dslnuts.com/files/cmtu10017.zip download this tool unzip it and run it put 1500 in apply changes and reboot take another analyzer like you did above to see if it changed.

[jefa111]

Yes, I am behind a router. The MTU setting in the router is set to 1500. I tried the cmtu tool and it did not change anything. When I look in my registry it shows 1500 but the analyzer does not show this.

[mccoffee]

What make and brand of router do you have
It could be I have seen where the analyzer not reading the mtu right due to a router between ur home and the analyzer so it could be a fluke but


Also do you have any virtual private networking software installed or Interent connection sharring software installed if so ingore the bottom.



I would also try maybe deleting ur connection in my computer control panel network and dialup connections click on ur currnet connection highlight tcpip and click remove and make sure all the boxes are not checked when removing. Reboot when everything is gone then

Go back to network dialup connections and click make new connection and follow the wizard again i hoping windows will set it back to 1500.

[jefa111]

I'm using a netgear RP614 v2. Also, deleting and re-adding the connection did not work. I'll remove the router and try it that way...

[mccoffee]

Ok with the netgear this is a common promblem let me download the manual i forgot the exect steps on how to fix it let read real quick and see.

[mccoffee]

Sorry to double post but i want to make sure you read this is ur firmware up to date i guess your router has a bug with the mtu that newere firmware fixes??

[jefa111]

I have the newest firmware, and the analizer gives proper results without the router.

[mccoffee]

Then don't worry about it still tweak for 1500 sorry about all th steps just wanted to make sure

[jefa111]

ok, thanks. I appreciate the asssist.

[Andrzej]

:D jefa111 unfortunately yours router have MTU stuck.

in my MTU stuck collection
I can find:
...Netgear Router Model Number: RP614v2 FirmWare: 5.14RC1
MTU = 1440 MSS = 1400
MTU stuck - problem's solution : unknown...