Built-in iSight problem on iChat w/ Macbook Pro

Question

when i try to invite people to see my iSight, it says connection failed because Ididn't respond. This has happened almost every single time I have tried to connect. The only 2 times it has worked, one of the times it disconnected after a few minutes. The other time was just a few minutes ago when my dad and I connected with our iSights. Although it worked with my Dad and I, it didn't work with 2 other people both immediatly before and after my dad and I connected.
I found this answer but have no idea what it means. someone said it worked for them but i am not a computer genious. anyone know how to help?
the answer i found: If it isn't your Firewall settings, what kind of router are you using and does it use UPnP?
If it does, try toggling UPnP off and on again, then connecting. Also, you might want to try using a different MTU setting. The Ralph Johns site has some recommendations on values to use.
This happens to me with my brother and toggling the UPnP solves it (Netgear D834G router). However, if I turn off or reboot my router, I have to toggle the option once more to get video chats working again.
macbook pro   Mac OS X (10.4.6)  

Answer 1

Hi Molly,
Ok UPnP stands for Universal Plug and Play.
This is a means where the Application on the computer instructs the modem to open the ports it needs.
It allows multiple computers and other devices on your LAN to use the same ports at the same time.
This means that the router or modem can be left in it's default mode which is likely to be DHCP.
Ok so now DHCP is a means whereby the router or modem gives out IP addresses to the devices and computers on your LAN.
Your computer keeps the same IP until the lease time runs out. If the computer is on and connected to the DHCP serving device then the DHCP lease is renewed. If it is off or unconnected at the time the lease runs out then the IP gets changed the next time the computer is tunred on. (with a Mac this also includes Sleep). It acts as if it is a new computer on the LAN is one way of looking at it.
So if you use Port Forwarding and DHCP there is a chance your computer's IP will change at times. As the Port Forwarding points to one IP on the LAN it may not always be pointing to your computer.
As you are using UPnP which means any IP can have the ports open it does not matter if your computer's IP changes with using DHCP.
Now your computer and modem (or router) can be set up so that the IP to the computer never changes. This is called Static routing.
It is created by turning Off DHCP in the modem or router.
A change needs to be made on the Mac in System Preferences > Network > Connection method >TCP/IP tab.
In the drop down that reads Using DHCP now needs to be changed to read Manually.
After this you need to type in the IP in the filed underneath that the computer is going to use.
Alonmg with the Subnet Mask and "router" IP info and possibly the DNS server info if you have it.
Now the IP you choose needs to be in the same range the Modem or router is using.
So if your modem is at 192.168.1.100 then your computer needs to be any number in 192.168.1.xxx except for .100 as long as it is between 1 and 255.
The other info should be copied from the Using DHCP settings
(Subnet Mask, DNS Servers and "router" IP address).
Hope this is some use.
11:03 PM Thursday; June 1, 2006