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Windows 7: Can I change MTU


28 Nov 2009   #1

Windows 7
 
 
Can I change MTU

Where can I change MTU to say something like 1452 - I am running PPPoE and the router is dropping packets. I get 500Mbits when connected directly to modem and 50Mbits when connected through router.

Thanks in advance

Anatol

My System SpecsSystem Spec
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28 Nov 2009   #2

Windows 7 x64 HP, Windows 7 HP, Windows 7 Ult
 
 

Quote   Quote: Originally Posted by anatol View Post
Where can I change MTU to say something like 1452 - I am running PPPoE and the router is dropping packets. I get 500Mbits when connected directly to modem and 50Mbits when connected through router.

Thanks in advance

Anatol
Welcome to Seven Forums, anatol.

You can change the MTU in the router. Depending on the type, the place to change it will be called different things, but look for "Setup" or "Basic setup" when you log onto the router.

Try setting it equal to the MTU value in the modem.

(The receive buffer value in the network interface card (NIC) will be set to a lot less - probably 256 - don't worry about that.)
My System SpecsSystem Spec
28 Nov 2009   #3

Windows 7
 
 

My System SpecsSystem Spec
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28 Nov 2009   #4

Windows 7 x64 HP, Windows 7 HP, Windows 7 Ult
 
 

Since you don't have the problem when directly connecting to the modem, but do when you connect through the router, that tells me that the router is somehow involved.

While it is true that the originating system has a role in the size, once it hits the Internet, the "originator" to you is the last switch in the line - your ISP.

All that said, it is possible that the connection between your system and the router is causing problems. Is the connection wireless to the router? If it is, check for interferrence near the router - lights, monitor, etc.
My System SpecsSystem Spec
28 Nov 2009   #5

Windows 7
 
 

I am using wired connection to the router. The best explanation why MTU needs to be changed on the computer can be found at Max MTU: How do I find mine? Tweaking FAQ - dslreports.com ...
My System SpecsSystem Spec
02 Dec 2009   #6

Windows 7
 
 

The answer to my question is:
Run netsh as Administrator

netsh>interface ipv4
netsh interface ipv4>show interface

Idx Met MTU State Name
--- ---------- ---------- ------------ ---------------------------
1 50 4294967295 connected Loopback Pseudo-Interface 1
11 10 1500 connected Local Area Connection

netsh interface ipv4>set interface "Local Area Connection" mtu=1452
Ok.
netsh interface ipv4>show interface

Idx Met MTU State Name
--- ---------- ---------- ------------ ---------------------------
1 50 4294967295 connected Loopback Pseudo-Interface 1
11 10 1452 connected Local Area Connection

netsh interface ipv4>bye


Did it solve my problem - that is a different question
My System SpecsSystem Spec
02 Dec 2009   #7

7600.20510 x86
 
 

Windows 7 auto tunes. No need to adjust anything.

Set the router back to factory settings.
My System SpecsSystem Spec
07 Dec 2009   #8

Windows 7 Pro 64-bit
 
 

Quote   Quote: Originally Posted by torrentg View Post
Windows 7 auto tunes. No need to adjust anything.

Set the router back to factory settings.
Wow! Autotunes - really? So, I don't need to set the MTU to 1492 like I did in XP? That's great! One less tweak I have to do. Way to go MS.
My System SpecsSystem Spec
07 Dec 2009   #9

Windows 8.1 Pro (x64)
 
 

Windows 7 is by default using Ethernet II which has an MTU of 1500 versus Ethernet (I or 802.3) which has an MTU of 1492. Most modern networks are using Ethernet II frames...if yours is not...well...
My System SpecsSystem Spec
07 Dec 2009   #10

 

For all of it's whistles and bells, Windows 7 support for ethernet devices lags far, far, short of that of Windows XP - and it's by no means clear whether all the intended improvements actually add real functionality...
My System SpecsSystem Spec
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 Can I change MTU




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