Network problems, with pics

[Jasonbot]

Here's a basic schematic of my network:

The problem is that when the iMac is connected to the internet it cannot see any other computer on the network. Irrespective of whether it's a mac or a PC. My mac's IP is also an internet based one while it seems that the PC's have 2 different IP's, one for network and one for internet?? Strangely enough the PC's can see eachother on the network while on the internet.

 

[aristobrat]

Is the wireless thing that's plugged into your router also acting as a router?

 

[Jasonbot]

Is the wireless thing that's plugged into your router also acting as a router?

Oh yeah, forgot to say:
The airport express is bridged and the router is also bridged for intenet access (PPPoE) because my family uses two different broadband accounts-long story.The router is set to DHCP for network addresses.

 

[peterjhill]

Oh yeah, forgot to say:
The airport express is bridged and the router is also bridged for intenet access (PPPoE) because my family uses two different broadband accounts-long story.The router is set to DHCP for network addresses.

Your machines cannot talk to each other because they have no route to each other..

If the mac is doing PPPoE, then it has an address from your ISP. Its default gateway is to the ISP.

What are the IP addresses of all interfaces and subnetmasks for those addresses for all the machines?

 

[Jasonbot]

What are the IP addresses of all interfaces and subnetmasks for those addresses for all the machines?

I see my mac IP and gaeway are from my ISP but now WHy does my PC have network and internet connection at the same time?

My iMac has an IP of 41.242.xxx.xx with no subnet mask and a router of 41.241.xxx.x The PC's have two little connection icons on the system tray which both display different sets of data. But I think I fixed it All I did was to make another Location in Network settings yay. I sorted my own problem. I am t3h 1337 1!!!!!111!one!!1