IChatAV possibly problems with router, any ideas please?

Question

Can anyone please help me?
I have spent a few days trying to work out what is wrong with my network/computer setup that prevents video chat working to computers that are not on my LAN. I have read just about every forum and post that looks meaningful but am struggling now.
Once upon a time it all just worked (with tiger). Now that I have a use for it..... obviously it doesn't.
My set-up is a little complicated but I can't believe its too unusual. I have a couple of macs and PCs running leopard with all the latest patches (although ichat had stopped working before the leopard upgrade). The LAN uses 192.168.1.0/24. I have a linux based router (openwrt-white russian 0.9 WRT-54GS) which runs amongst other things an asterisk SIP server (on port 5060). But while the versions of software have changed (mainly to try and get iChat working), it is still the same set up that used to work. There is an airport extreme on the LAN as well but that is in bridge mode and used as a 802.11n AP and printer server. My DSL modem is a Dlink DSL-302G which is running in half bridge mode which terminates the ASP's PPP session and presents IP packets addressed to the router which is provided with the PPP supplied IP address using DHCP. The router therefore is effectively connected directly to the ISP, there is no NAT in the DSL modem, only the router.
My ISP now offers a SIP based VoIP service which I use via asterisk on the router. The asterisk server also uses several other SIP based providers for both incoming and outgoing calls but these have been there for a long time and still work fine, so the ISP isn't messing with SIP messages.
As I have said this set-up once all worked fine with iChat over the internet. Now all that works is text.
iChat does work between machines on my LAN where I can do text, audio, video and screen sharing. I assume that this means that ports to external co-ordinating entities are working through the router. Non of the LAN machines have a firewall configured on them.
When I try and set up an AV chat with a remote machine I get to the "Starting video chat with..." and then after 10-15 seconds I get an error:-
Disconnected from video chat because:
Did not receive a response from xxxx xxxx
When I try and set up an AV chat with appleu3test01 I get a different message saying "appleu3test01 cancelled the connection which I am assuming is just something timing out quicker on the bot and causing it to cancel the call before the setup protocol times out.
I have messed with the router adding and removing different uPNP agents but as far as I can tell they are working. I can see that UDP port 16402 has been set up for forwarding to the my imac.
When calling a friend, I have run network traces on the mac and both LAN and WAN ports of the router. I don't have any information on the AIM protocols to see if the problem is in there. I can provide the traces if this is useful. I do notice that SIP messages are being sent to my friends internet IP address but that they only contain my machine's LAN IP address ...
INVITE sip:user@{friend's WAN IP addr}:16402 SIP/2.0
Via: SIP/2.0/UDP 192.168.1.4:16402;branch=z9hG4bK1cf33cfb08dfaaca
Max-Forwards: 70
To: "{friend's name}@mac.com3" <sip:user@{friend's WAN IP addr}:16402>
From: "my name" <sip:[email protected]:16402>;tag=149537885
Call-ID: bcb4f7d8-d235-11dc-a3aa-b2953c604012@192-168-1-4
CSeq: 1 INVITE
Contact: <sip:[email protected]:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 736
.....snip....
Is this correct? UDP port 16402 has been upnp configured in the router to DNAT to 192.168.1.4:16402 which is the machine I made the call on. I do not receive a response to this message or any other SIP messages from my friend. I can see a upnp conversation between the mac and the router which asks for an external ip address which is provided. I can also see this external IP address being used in some AIM message fields.
Any ideas gratefully received and I can send significantly more information if required.
Thanks if you read this far.
Steve

Answer 1

Ralph, Thanks for replying. There where no received SIP messages at all just the INVITE being sent but I have made some more progress. The mini does indeed just work. I can do everything that you are supposed to do to other ichat users on the internet. Very nice.
The imac is still playing up but I have got further. I had peerguardian2 installed which unknown to me doesn't need to be running to prevent you for accessing 'barred' IP addresses. snatmap.mac.com is barred in the lists! I discovered this when I saw one of your other posts showed how to turn on terminal logging for ichat. Now that I have turned off peerguardian2 (using the disable filters option) I can make calls to the testbot and see the adverts. I have even done a video conference with the two testbots. I will just uninstall peerguardian2.
However, I can not get a AV chat working to a real user....
In response to your suggestions:-
I have tried all the options for quicktime streaming but will try 1.5Mb/s again.
The ichat bandwidth limit is set to "none". I am in New Zealand and I have standard ADSL (not ADSL2+) 7.6M down 512K up. The mini config is also set to none.
Internet sharing is off.
I have had parallels on the machine but the two interfaces that it installed "Parallels Host-Guest" and "Parallels NAT" are configured 'off' and show as not connected. Is this enough? I will uninstall parallels and see if that helps since I don't use it. I also have VMware's thing installed but that doesn't seem to add any interfaces.
I need to capture a full trace of the imac to other ichat user to see what is happening but will update when I have does your suggested changes or have a trace
Thanks again