ddan,

Saw your other thread, lets hope we get some response.

I have been doing some investigating over past few days about cable networks, modems and routers.

At first I thought the cable modem was the cause of our problems as I found a reivew on the net from someone with the same modem and they had the same thing as us. They ended up purchasing a new modem (which unfortunately we can't do) and their problem went away.

I went into the modem's configuration (http://192.168.100.1) and reset everything to the default settings. This wipes all of the modem's learned MAC addresses. I restarted the modem so it could just learn the router's MAC address. Didn't work.

I have found out that cable networks can block certain MAC addresses, so I cloned my PC's MAC address into the router and did the same thing as above. Didn't work.

Although trying the above didn't completly work, I did improve my connectivity from about 1% to 50%, allbeit this only lasted until everything was powered off and on and now I am back to nothing again.

I also found an interesting forum which might shed some light on what our problem could be. (Not exactly sure how to post links here so I'll just paste it.)

http://www.cable-modems.org/forum/read.php?f=2&i=497&t=497

It is quite a long thread so I'll quote the main thing from someone who sounds like they know what they're talking about:

[start]Re: Comcast Linksys Router Problem
Author: Chip Schweiss (---.stl1.dsl.speakeasy.net)
Date: 05-29-05 22:05

I've been investigating this problems for quite the past several days. My background is very in depth with TCP/IP problem diagnosis at the network level, including writing my own TCP stack.

I've been examining the behavior of Linksys WRT54G(s) routers against Charter Pipeline by sniffing the packets on the wire as DHCP happens.

It looks to me that this truely is an ongoing problem of the cable companies believing they have a right to charge for every computer connected to the cable connection, just as they want to charge for every television set. The fed says they cannot, so they have to play technical warfare against routers. It just amases me the arrogance of Charter when I can prove the router working on any network besides theirs, and they will still say your router is broken.

DHCP is a very simple protocal, but has some very distinct fitures that give router devices away from Windows machines. Part of the DHCP discovery packet is an identifier of the client software sending the DHCP request. The MAC address seems to be the first approach the cable companies have taken against routers since the first part of all mac addresses identifies the manufacture of the ethernet device. Since MAC clone is a standard feature of many retail routers this has proven not to be that effective. The next step is to identify by the contents of the DHCP packets themselves. Since most routers are either embeded Linux or other platforms that fit in small packages they use specialty DHCP clients. I'd bet that nearly 90% of the home based routers (Linksys, Belkin, etc.) all use udhcpc which is part of the busybox package for embeded devices. This client clearly identifies itself in the DHCP discovery packet. Not to hard at all to detect.

I'm going to have a hack at udhcpc on my Linksys router and make it mimic a Windows XP DHCP client. I wouldn't be surprised all I have to do is change the client identification in the discovery packet to match Windows and all the problems will go away.

Once I have a solution to this problem these bastard cable companies keep saying "It's your unsupported router" I'll be the first to turn the proof of their nasty ways over to Linksys (Cisco) so they can sue Charter for anti-competive practics which the Fed has forbiden them from doing as part of their bargain to maintain a monopoly on the cable lines.[end]

If the above is correct then telstra is our problem and a big one at that. There are two things we could try:

1. Tricking telstra into thinking our routers are actually PC's (as above).
2. Hiding our routers behind something (my router worked at the PC shop because it was hidden behind a switchboard or something like that and the telstra couldn't see it).

Another thing I thought of is that telstra must have done some sort of software upgrade to their network around the end of last month, which would explain the fact that both our routers were working before and all of a sudden they stopped.

I am just typing this up at work and the IT guy just walked in so I asked him about it. He said that telstra has just done upgrades, but this was for the new digital tv and only in certain areas. He asked me to bring my router to work and he will test it at home on his cable network. Will let you know how that goes later.

Sorry this post is so big, I just thought I should share everything I find out in the hope that someone out there might be able to help us.