Ok, thanks for the updates. Just to be sure, what are the model numbers of each of your base stations. For example, a 1st generation Extreme would be: A1143. A 1st generation Express would be: A1264. Do these match yours?
If so, then let's start with adding one Express back into the network. Doesn't matter which one you choose. Please perform the following steps. When done, you should have a working roaming network with just the Extreme and 1st Express. Once verified that it is working, we can add the 2nd Express following the steps for adding an additional station.
The following are step-by-step instructions, using version 6.x of the AirPort Utility in manual mode, to configure a roaming network.
First, there are a few key elements to successfully configuring a roaming network, and they are:
- All of the base station must be interconnected by Ethernet. Note: You can use non-Apple routers in this type of network.
- All base stations must have unique Base Station Names.
- All base stations must use the same Radio Mode and Wireless Security Type/Password.
- Each base station should be on a different Radio Channel. Using "Automatic" works well here.
- All base stations, other than the "main" base station, must be reconfigured as a bridge.
Let's start with the "main" base station. This will be the one directly connected to the Internet modem:
- AirPort Utility > Select the "main" base station > Edit
- Base Station tab > Base Station Name > Enter a unique name here
- Internet tab > Connect Using: DHCP
- Wireless tab > Network Mode: Create a wireless network > Wireless Network Name > Enter the desired name. This will be used on all base stations > Wireless Security: WPA2 Personal (recommended) > Wireless Password > Enter the desired wireless password. This will be used on all base stations.
- Network tab > Router Mode: DHCP and NAT
- Click on Update
For each additional base station added to the roaming network:
- AirPort Utility > Select the appropriate base station > Edit
- Base Station tab > Base Station Name > Enter a unique name here
- Internet tab > Connect Using: DHCP
- Wireless tab > Network Mode: Create a wireless network > Wireless Network Name > Enter the desired name. This will be used on all base stations > Wireless Security: WPA2 Personal (recommended) > Wireless Password > Enter the desired wireless password. This will be used on all base stations.
- Network tab > Router Mode: Off (Bridge Mode)
- Click on Update