IChat AV worked - but not anymore!

Question

Hello,
A week ago I tried to do my first iChat AV session with my new internet set up:
iChat Version 4.0.8 (619)
iMac IC2Duo 2.4 Ghz (with Airport card) runing OS X 10.5.8
Airport Express in bridge mode (I love AirTunes!)
Gateway 2wire 2701HG-G wireless modem (ADSL in DHCP)
Since it did not work, I did some reading on the Apple Forums. I managed to reboot the modem, set up 'Port Forwarding' for that modem and bingo: iChat AV worked beautifully, with my Apple firewall on (but allowing iChat connections) and Screen sharing on. I could even see my friends' screen, a beauty!
But now, 6 days later, iChat AV no longer works. iChat text works fine. I can't even do a session with Appleutest3test02.
I think it has to do with DHCP leases b/c as I look through my Mac's and modem's configuration, I noticed one (or more) of the IPs changed. The modem is set to release it's IP Lease every 72 hours, some that probably messes it up.
I've been trying to read some more, but this one is beyond me: I'm stumped. I'm not sure if I can/should make the modem stick to a single IP + I don't know how to 'reset' my Mac's/iChat's/Airport's settings to allow the new IPs.
Hopefully someone knows how this works (below is the Error report without the binary image descriptions)
Thanks ahead of time!
Marc
(in Montréal)
Date/Time: 2010-01-10 21:56:44.768 -0500
OS Version: 10.5.8 (Build 9L30)
Report Version: 4
iChat Connection Log:
2010-01-10 21:56:06 -0500: AVChat started with ID 958764371.
2010-01-10 21:56:06 -0500: [email protected]: State change from AVChatNoState to AVChatStateWaiting.
2010-01-10 21:56:06 -0500: 0x197ae7b0: State change from AVChatNoState to AVChatStateInvited.
2010-01-10 21:56:12 -0500: 0x197ae7b0: State change from AVChatStateInvited to AVChatStateConnecting.
2010-01-10 21:56:12 -0500: [email protected]: State change from AVChatStateWaiting to AVChatStateConnecting.
2010-01-10 21:56:41 -0500: 0x197ae7b0: State change from AVChatStateConnecting to AVChatStateEnded.
2010-01-10 21:56:41 -0500: 0x197ae7b0: Error -8 (Did not receive a response from 0x197ae7b0.)
2010-01-10 21:56:41 -0500: [email protected]: State change from AVChatStateConnecting to AVChatStateEnded.
2010-01-10 21:56:41 -0500: [email protected]: Error -8 (Did not receive a response from 0x197ae7b0.)
Video Conference Error Report:
19.646151 @SIP/SIP.c:2719 type=4 (900A0015/0)
[SIPConnectIPPort failed]
408.911226 @SIP/SIP.c:2719 type=4 (900A0015/0)
[SIPConnectIPPort failed]
2342.176778 @SIP/SIP.c:2719 type=4 (900A0015/0)
[SIPConnectIPPort failed]
Video Conference Support Report:
6.202801 @Video Conference/VCInitiateConference.m:1584 type=2 (00000000/0)
[Connection Data for call id: 1 returns 1
6.627839 @Video Conference/VCInitiateConference.m:1599 type=2 (00000000/0)
[Prepare Connection With Remote Data - remote VCConnectionData: 1, local VCConnectionData: 1
6.628484 @Video Conference/VCInitiateConference.m:1703 type=2 (00000000/0)
[Initiate Conference To User: u0 with Remote VCConnectionData: 1 with Local Connection Data: 1 conferenceSettings: 1]
17.646155 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK1ef3a2667c984ef1
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=29670684
Call-ID: 7ee4f4da-fe57-11de-ad66-d6fd22894012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 734
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:2334027546
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:1300742612
18.146550 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK1ef3a2667c984ef1
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=29670684
Call-ID: 7ee4f4da-fe57-11de-ad66-d6fd22894012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 734
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:2334027546
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:1300742612
19.146895 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK1ef3a2667c984ef1
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=29670684
Call-ID: 7ee4f4da-fe57-11de-ad66-d6fd22894012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 734
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:2334027546
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:1300742612
395.491698 @Video Conference/VCInitiateConference.m:1584 type=2 (00000000/0)
[Connection Data for call id: 3 returns 1
395.896410 @Video Conference/VCInitiateConference.m:1599 type=2 (00000000/0)
[Prepare Connection With Remote Data - remote VCConnectionData: 1, local VCConnectionData: 1
395.897066 @Video Conference/VCInitiateConference.m:1703 type=2 (00000000/0)
[Initiate Conference To User: u0 with Remote VCConnectionData: 1 with Local Connection Data: 1 conferenceSettings: 1]
406.911181 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK622027071d300a24
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=247917092
Call-ID: 66ea2f20-fe58-11de-ad66-aa12ea324012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 733
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:3546553127
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:874043033
407.411719 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK622027071d300a24
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=247917092
Call-ID: 66ea2f20-fe58-11de-ad66-aa12ea324012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 733
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:3546553127
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:874043033
408.412082 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK622027071d300a24
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=247917092
Call-ID: 66ea2f20-fe58-11de-ad66-aa12ea324012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 733
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:3546553127
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:874043033
2328.774596 @Video Conference/VCInitiateConference.m:1584 type=2 (00000000/0)
[Connection Data for call id: 5 returns 1
2329.161191 @Video Conference/VCInitiateConference.m:1599 type=2 (00000000/0)
[Prepare Connection With Remote Data - remote VCConnectionData: 1, local VCConnectionData: 1
2329.161789 @Video Conference/VCInitiateConference.m:1703 type=2 (00000000/0)
[Initiate Conference To User: u0 with Remote VCConnectionData: 1 with Local Connection Data: 1 conferenceSettings: 1]
2340.175985 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK3bc98d4b6027438f
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=1721667789
Call-ID: e73b8008-fe5c-11de-ad66-f1bf65f54012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 734
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:1990577082
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:2065781344
2340.676327 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK3bc98d4b6027438f
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=1721667789
Call-ID: e73b8008-fe5c-11de-ad66-f1bf65f54012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 734
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:1990577082
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:2065781344
2341.676605 @SIP/Transport.c:2362 type=1 (00000000/0)
[INVITE sip:user@rip:16402 SIP/2.0
Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK3bc98d4b6027438f
Max-Forwards: 70
To: "u0" <sip:user@rip:16402>
From: "0" <sip:user@lip:16402>;tag=1721667789
Call-ID: e73b8008-fe5c-11de-ad66-f1bf65f54012@lip
CSeq: 1 INVITE
Contact: <sip:user@lip:16402>;isfocus
User-Agent: Viceroy 1.3
Content-Type: application/sdp
Content-Length: 734
v=0
o=Marc 0 0 IN IP4 lip
s=0
c=IN IP4 lip
b=AS:2147483647
t=0 0
a=hwi:1056:2:2400
a=iChatEncryption:NO
a=bandwidthDetection:YES
m=audio 16402 RTP/AVP 110 121 12 3 0
a=rtcp:16402
a=rtpmap:121 speex/16000
a=rtpmap:122 speex/8000
a=rtpmap:113 X-AAC_LD/44100
a=rtpmap:110 X-AAC_LD/22050
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpID:1990577082
m=video 16402 RTP/AVP 123 126 34
a=rtcp:16402
a=rtpmap:123 H264/90000
a=rtpmap:126 X-H264/90000
a=rtpmap:34 H263/90000
a=fmtp:34 imagesize 1 rules 30:352:288
a=framerate:30
a=RTCP:AUDIO 16402 VIDEO 16402
a=fmtp:126 imagesize 0 rules 20:640:480:640:480:20
a=fmtp:123 imagesize 0 rules 20:640:480:640:480:20
a=rtpID:2065781344
Video Conference User Report:
0.000000 @:0 type=5 (00000000/16402)
[Local SIP port]
0.000017 @:0 type=5 (00000000/16402)
[Local SIP port]
25.642722 @Video Conference/VideoConferenceMultiController.m:1474 type=5 (00000000/0)
[IP And Port Data With Caller IP And Port Data: Obtained 160 bytes of local IP and port data (4 entries). Remote data was 0 bytes (0 entries).
414.907584 @Video Conference/VideoConferenceMultiController.m:1474 type=5 (00000000/0)
[IP And Port Data With Caller IP And Port Data: Obtained 160 bytes of local IP and port data (4 entries). Remote data was 0 bytes (0 entries).
2348.172808 @Video Conference/VideoConferenceMultiController.m:1474 type=5 (00000000/0)
[IP And Port Data With Caller IP And Port Data: Obtained 160 bytes of local IP and port data (4 entries). Remote data was 0 bytes (0 entries).
[]

Answer 1

Hi,
In most cases the ISP uses DHCP to give your Modem an IP - called your Public IP.
In the case of a cable modem it is likely that it does not route and will pass the Public IP on to the next device, computer or router.
A DSL modem might well route.
So if the modem routes it will not pass the Public IP on and will issues a set of LAN IPs to a router or computer.
By Default it will be set to Issues the IPs automatically using DHCP.
Routers and computers by default ask to get an IP by DHCP.
Routers and modems recognise not to pass on Public IPs when the route. However they will pass on LAN IPs meaning you can have your computer getting two IPs from a modem that routes and a router that is in between.
There are several ways to stop a modem or router issuing IPs to computers.
On some modems you can put them in to what is called Bridge Mode. Effectively all routing action is stopped and it becomes like the older dial-up modem except it is most likely Ethernet cables running to it.
You can also set it to Static Routing. In This DHCP is turned off in the Modem or router and you manually enter the info several text fields on the computer or router that comes next.
You need the IP of the Routing Device (Sometimes called Gateway IP) and the Subnet Mask and DNS servers info. You then choose the IP that the computer or router is going to use. (Like the Pic I showed earlier).
There are limited set of IPs that are reserved for LAN IP addresses.
Anything start 192.168.xxx.xxx
Anything starting 10.xxx.xxx.xxx
A range between 172.16.xxx.xxx through to 172.32.xxx.xxx
(In these cases xxx stands for a number between 0 and 254 or 1 and 255 - there are only 255 numbers but some go 0 to 245 and some 1 to 255)
Having two DHCP servers on your LAN is considered to be not good Networking.
A small number of routers can be put into Bridge Mode - like Airport devices - which then leave the Modem, if it routes, doing DHCP.
Pause.
<hr>
Ok. In setting this up you may lose Internet Connection at various stages whilst you set things up.
Lets take a Cable Modem first that does not route.
We do not have to worry about anything until we get to the router to computer part (provided you have Internet Connection AND can Web Browse and get Mail in your favoured Apps)
IF the Router does UPnP or in the case of an Airport Device, Port Mapping Protocol (PMP or NAT-PMP) then this can be used as both methods allow the apps to have the ports they want open and will also allow Multiple Computers to use the same ports - so if the IP changes then the computer and app can still work.
Lets presume we want to set Static (Manually on the Mac) routing anyway.
In the case of the Airport Base Station this is fairly simple.
You go to Applications/Utilities on the Mac and a open the Airport Utility.
If several Airports show Up then you select your one.
You then use the Edit Buttons to get to the Internet iCon Pane.
At the bottom it has a drop down which by default is set to Share a Public IP (it presumes a Cable modem but will share the the IP (Connect computers to the IP) it is getting Upstream side).
You needs some info first from the top part of the Screen.
DNS Server, Subnet Mask and the IP the Airport Base Station is using on the LAN Side (It will be one of the ranges shown above - older models tend to be 10.0.1.1 and later ones 192.168.1.1)
You can now set "Share A Public IP" drop down to "Bridge (Off) Mode.
You will now lose the Internet.
On the Mac In System > Preferences > Network you need to select either Ethernet or Airport depending how you connect to the Airport Base Station.
Set the drop down to Manually.
In Ethernet you can enter the Info in the required boxes.
In Airport you have to use the Advanced Button and then the tabs.
You can then choose the IP to use.
If the Airport is at 10.0.1.1 then it can be anything between 10.0.1.2 and 10.0.1.255 (The first three give you the range of IPs and must match the first three of the Airport Base Station's number. You cannot chose the IP the Base Station has or exceed the 255 number (or 254 on ones that use zeros).
So from the top in Ethernet it will read:-
Manually in the drop down
192.168.1.2 (Presuming the "Router IP" is 192.168.1.1)
Subnet Mask 255.255.255.0 (this is a common example)
DNS Servers 4.2.2.2, 4.2.2.3 (these are two Public DNS Servers but your modem should make your ISP's appear in the Airport Base station from the ISP)
Router IP = 192.168.1.1 (in this Example).
You should now have the Internet back.
Repeat on other computers.
Re 1)
Lease times.
Most devices will drop the Lease only when the computer is turned Off and left Off past the lease time.
Also most will have a setting that may read shorter but is continuous.
On some devices you can set Reserved IPs for the relevant Card on the computer (Airport or Ethernet) by it's Individual ID called it's Media Access Card address, MAC in capitals for short). The naming of this Reservation can vary device to device (infinity, Reservation, Extended Lease).
Re 2) I think I have covered this above.
Re 3) as I have said the Lease time is not so important.
If you have several computers it can pay to turn them on in the same order if you turn them Off or set Static/Manual routing.
Re 4) IPv4 and IPv6 actually give your Ethernet card two MAC addresses.
This can create issues if your ISP supports IPv6.
It can pay to turn this Off.
What we need to know here is what is the modem doing as far as routing is concerned ?
If you have a cable modem that does not route and the Airport is in Bridge Mode then you should see the Public IP from the ISP.
Tell us the first two parts of the Number please.
Re 5)
Not all devices do permanent Linking of MAC addresses or even computer/router names to hold IPs as you can set Static Routing.
Re 6)
It will be easier if you tell us the Device Make and Model number as there are site where we can link you to Pics. (and look at wording ourselves)
Re 7)
This has too many variables based on the answer to 6) and the semantics of different device manufacturers to offer a clear answer here.
Going back to my Pic though, you can set the number of IPs in the DHCP range on some devices.
You can in fact use a mixture of Static IPs and a reduced range of DHCP Issued ones.In this case it may pay for you to post a pic On-Line somewhere for us to see or email a me a pic of the Screen Shot of that page. (my email can be found clicking my name on the left).
Summary,
I think I have covered the broader bits you have not discovered yet although I have left out about which ports are open by default if you are not using UPnP in the modem.
(I have also written with an eye to other readers and other devices)
I have listed the way to set Static routing.
Using UPnP does away with worrying about the IP changing in the set up you describe.
The IP changing only becomes important if the modem is using Port Forwarding to open the ports for iChat (Or it's extreme form of DMZ).
Could you confirm that this is what you are doing ?
Can you answer the question or post new ones if you have not under stood anything ?
Basically Routing DSL modem to Airport in Bridge Mode to computer is good.
It will be about how the ports are opened that will govern how you proceed from here.
8:12 PM Sunday; January 17, 2010
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"