Router Changes MTU

Lee_Nover · Post by **Lee_Nover** » Mon Dec 15, 2003 10:41 am

My MTU is now 1372 when I installed my router. It use to be 1500. My MSS is now 1332. I use cablenut and I am entering the correct info, my the router is changing the values. When I disconnect the router, it's fine. Can somebody help me? It's a cable connection. My forware does not allow me to configure MTU/MSS values.

mccoffee · Post by **mccoffee** » Mon Dec 15, 2003 10:52 am

What model of router and make??

http://www.dslreports.com/tweaks take this test with router plugged in. See if your mtu is right on this test.

Lee_Nover · Post by **Lee_Nover** » Mon Dec 15, 2003 11:00 am

It's an Actiontech R3010SUW. Here are the specs. Don't know if it helps.

Specifications GENERAL

Operating System:
Windows 95, Windows 98, Windows 98SE, Windows ME, Windows NT 5.0, Windows 2000, Windows XP, MacOS 7.1 and higher;
USB: Windows 98, 98SE, Windows ME, Windows 2000, Windows XP

Interface:
Ethernet (models available in 4-Port & 1-Port), USB and Wireless
Security:
IP Masquerading (NAT), Web site blocking, Web service blocking, Internet activity logging
Setup and Management:
Web based
Standards Compliance:
RFC 2516, IEEE 802.3 10 BASE-T Ethernet, IEEE 802.3u 100 BASE-Tx Fast Ethernet, USB 1.1/1.0, IEEE 802.11b
Protocols Supported:
RFC 25216 (PPPoE), TCP, IP, UDP, DHCP (client, server), DNS (client), TFTP (client, server), FTP, Telnet, HTTP, SMTP, POP3
VPN Support:
L2TP, PPTP, IPSec (all pass-through)
Maximum Computer Users Supported:
253

WIRELESS

Industry Standard:
IEEE 802.11b
Frequency Band:
2.4 GHz
Uses Direct Sequence Spread Spectrum:
Yes
Maximum Data Rate:
Up to 11Mbps
Data Encryption Supported:
64 bit & 128-bit WEP
Range:
Up to 300 feet indoors

Lee_Nover · Post by **Lee_Nover** » Mon Dec 15, 2003 11:14 am

DSL Reports and TCP Analyzer give me the same MTU value. Even went into the reg where is has 1460 in the key.

mccoffee · Post by **mccoffee** » Mon Dec 15, 2003 12:05 pm

See if this helps if not call them there website was no use usaully it will show how to adjust mtu.

http://www.actiontecsupport.com/broadba ... 010075.exe this is the latest firmware download it if you haven't already. INSTALLATION INSTRUCTIONS - PLEASE READ CAREFULLY!
You may want to print these instructions.

Create a folder on your C: drive.
Download the firmware upgrade to that folder.
Make sure your router/gateway is connected to this computer.
Open "Windows Explorer" and go to the directory the archive file was downloaded into.
Double-click on the executable file that you just downloaded.
Click "OK" in the window that appears. The file is extracted.
Click "OK" in the "upgrade" screen.
Make sure the input IP address is the same as the IP address of your gateway/router. If not, enter the correct IP address in the lower text box.
Click "Start".
NOTE: The upgrade process will take about 3-6 minutes. Please do not interrupt the upgrade process before completion. This program will automatically close upon completion. Before using your Router/Gateway again, make sure to turn it OFF and then ON.

Lee_Nover · Post by **Lee_Nover** » Mon Dec 15, 2003 12:28 pm

I have already updated the firmware to that version. As well, I called tech support and they were not helpful, to put it politely. I don't know what to do... I am stumped. My performance has decreased a little because of it.

mnosteele52 · Post by **mnosteele52** » Mon Dec 15, 2003 3:45 pm

It's obviously your router, did you just recently purchase the router and notice the incorrect MTU? There is usually somewhere in the setup for the router to set your MTU value, yours should have one. Changing things in your registry won't help since the problem is not there.

mccoffee · Post by **mccoffee** » Mon Dec 15, 2003 7:29 pm

Goto your routers setup page and if anything that saids vpn or virtual private networking disable it.

Lee_Nover · Post by **Lee_Nover** » Mon Dec 15, 2003 8:52 pm

VPN is disabled. I just got the router and noticed MTU is incorrect. There is absolutely no option to change vale of MTU in the setup or advanced setup on the router page. Here are the results of the analyzer. Fussy devices.

TCP options string = 020405340103030001010402
MTU = 1372
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput.
MSS = 1332
MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

Default Receive Window (RWIN) = 43956
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 43956

RWIN is a multiple of MSS
Other values for RWIN that might work well with your current MTU/MSS:
511488 (MSS x 48 * scale factor of 8)
255744 (MSS x 48 * scale factor of 4)
127872 (MSS x 48 * scale factor of 2)
63936 (MSS x 48)
bandwidth * delay product:

Your RcvWindow limits you to: 1758.24 kbps (219.78 KBytes/s) @ 200ms
Your RcvWindow limits you to: 703.296 kbps (87.912 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 55 hops

TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00011100

Precedence (priority) = 100 (flash override)
Delay = 1 (low delay)
Throughput = 1 (high throughput)
Reliability = 0 (normal reliability)
Cost = 0 (normal cost)