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2 General

If you can access some, but not all websites or parts of some websites, experience FTP problems and/or cannot send and/or receive email, it may be caused by your MTU (maximum transmission Unit) size being set too high. Reducing the Maximum MTU size setting on the PC might correct this problem.

To determine the maximum MTU size for your Windows PC use the following procedure:
    •Open a Command or "DOS" Window.

    •Ping a known "pingable" address with the command:
    ping -f -l 1500 somesite.com

    •If the ping fails with the message "packet needs to be fragmented but DF set", keep trying the ping command but lower the packet size (1490, 1480, etc.) each time until you find a size that is successful.

    Add 28 more to this (since you specified ping packet size, not including IP/ICMP header of 28 bytes) And this is your MaxMTU.

    •Set the MaxMTU registry key on the PC to the successful packet size + 28. You can edit the registry manually or you can use a program such as DrTCP that will help you change the setting.

    •Reboot the PC.

    •Test the changes by trying to access a problem website or send/receive email.

Read this page for full details.
»Tweaking FAQ »Max MTU: How do I find mine?

by leevis See Profile edited by Doctor Olds See Profile
last modified: 2005-01-17 12:33:12

Troubleshooting Web GUI Connection to

Links below require the FREE Adobe Acrobat Reader:

Basic Router Troubleshooting Flowchart (13K PDF - Zipped)

Due to Efficient's mass deletion of web content this file no longer available:
Efficient Model 3060 Troubleshooting Flowchart (10K PDF)

Due to Efficient's mass deletion of web content this file no longer available:
Efficient Model 4060 Troubleshooting Flowchart (12K PDF)

Due to Efficient's mass deletion of web content this file no longer available:
Efficient Model 5260 Troubleshooting Flowchart (10K PDF)

Efficient Model 5667 Troubleshooting Flowchart (12K PDF - Zipped)

by Doctor Olds See Profile
last modified: 2004-03-15 03:31:48

Normal operation. You cannot access your server on the same LAN by using it's Domain Name (FQDN) or Public IP Address as loopback is completely disabled in quite a few SoHo Routers. It's a feature found in some, but not all Routers (it used be only in units starting at $600.00 and up until a few years ago). There is nothing you can do to enable loopback either. Sorry.

However, there are 3 work-a-rounds:

1) You can use the server's Private LAN IP to access it.
2) You can use a web proxy to access it (»www.guardster.com) by FQDN.
3) You can add an entry into your HOSTS file that shows your server domain name linked to the Private LAN IP.

by Doctor Olds See Profile
last modified: 2005-01-10 21:47:20

This Article at the Efficient KB should help:

Configuring Routers for Use with GameCube, GameSpy, PlayStation, XBox

by Doctor Olds See Profile

Due to historic problems for hosting any copyrighted Firmwares, we currently can only offer links to pages at official download locations.

SOHO Router: Kernel selection page [Covers Model #s 2601, 5660, 5711, 5781, 5851, 5861, 5871, 5950, and 7851 only]

Notation from the above page:

If you do not find a kernel that matches your part number call (877) 820-0005 for assistance.
Note: Using the wrong kernel can render your equipment useless and is not covered under warranty!

You can also follow the info from here:

Support and Service
»subscriber.communications.siemen ··· rt.shtml
Search the Siemens CPE Knowledge Base for the latest drivers and firmware.

Frequently Asked Questions:
»subscriber.communications.siemen ··· aq.shtml
For questions not answered here, please check our Knowledgebase:

Technical Reference

Accessing the Web Management Interface on my SpeedStream 5100 or 5200
Subnet Masks Chart
Basic Router Troubleshooting Flowchart (13K PDF)


Configuration Manager
SpeedStream Drivers
SpeedStream Kernels


Basic Security (Sample Firewall Script)
Implementing Security on 5700-, 5800-, 5900-, and 7000-series Routers (w/Sample Filters, Scripts)
IP Filtering Concepts (w/Sample Filters, Rules, Firewall Scripts)


Residential DSL Customer Premises Equipment (CPE) Warranty (2601/2602/2614/2623/3000-series/4000-series/5360/5667 USB-Enet DSL)
Residential Non-DSL Customer Premises Equipment (CPE) Warranty (1000-series/2005/2105)
5700/5800/5900-series Warranty

Feedback received on this FAQ entry:
  • http://www.lettronics.com/?page=lredownloads has 5861 kernel.f2k files for d/l

    2013-02-13 02:47:36 (germanbuick See Profile)

  • Nice, copyright problems. So how does that work out, now that the Efficient website (and probably company) doesn't exist anymore?

    2011-09-12 19:00:13 (Jurjen See Profile)

by Doctor Olds See Profile
last modified: 2006-02-25 04:52:13

Windows XP Compatibility/Drivers

by Doctor Olds See Profile

Product Registration (extends warranty to 2 Years for free!)

Note: Offer good on ALL product obtained after November 2001.

Program has been concluded. Thanks Efficient.

»store.efficient.com/OnlineStore/ ··· duct.jsp
Siemens Subscriber Networks, Inc., A Siemens Company
Hardware Extended Warranty Registration

Thank you for purchasing Siemens Subscriber Networks products. Our extended warranty program has concluded. Please see extended warranty card for conclusion details. SpeedStream products included in the extended warranty program were discontinued in June 2003. Henceforth the extended warranty program expired June 2004.

Products are covered by a standard one year warranty. Please maintain purchase documentation, as this will be needed for any warranty claims. Thank you.

by Doctor Olds See Profile
last modified: 2004-07-29 17:46:30

About NAT - How does Network Address Translation (NAT) work?

Feedback received on this FAQ entry:
  • Network Address Translation (NAT) is the process where a network device, usually a firewall, assigns a public address to a computer or group of computers inside a network. It limits the number of public IP addresses an organization or company must use. How it works. A computer inside a network makes a request to a computer on the Internet. Routers within the network recognize that the request is not for a resource inside the network, so they send the request to the firewall. The firewall sees the request from the computer with the internal IP. It then makes the same request to the Internet using its own public address, and returns the response from the Internet resource to the computer inside the private network. From the perspective of the resource on the Internet, it is sending information to the address of the firewall. From the perspective of the workstation, it appears that communication is directly with the site on the Internet. When used in this way, all users inside the private network access the Internet have the same public IP address when they use the Internet. That means only one public addresses is needed for hundreds or even thousands of users. Thus it allows the router to assign non-publically routable IP addresses to the computers on the network. This can be achieved in these forms: static, Dynamic, overloading and overlapping natting

    2013-11-14 08:17:40

by Doctor Olds See Profile

by Doctor Olds See Profile
last modified: 2004-07-05 03:04:31

Incident Report link (aka Problem or Complaint Report about their product).

»support.efficient.com/incident.h ··· ent.html

by Doctor Olds See Profile

Efficient.com KB Article #33693

About Straight-through vs Cross-over Ethernet Cables

by Doctor Olds See Profile
last modified: 2007-02-17 02:07:52