Your Zoom "modem" is a gateway device, which combines a modem and router in one package. As such, your Z5 gateway is providing DHCP and NAT services on your network.
With this type of device, AirPort Utility chose the correct Bridge Mode setting for your AEBS...since you only want one device on a network providing DHCP and NAT services.
In order to enable the Guest Network, the AEBS must be confiigured as the "main" router on the network providing DHCP and NAT services. Since it cannot do this when the Zoom device is already providing these services, the Guest Network feature is not available.
Sometimes, it is possible to configure the AEBS to act as a router anyway when there is another router on the network, but this can create IP address conflicts with two devices both trying to provide DHCP services for devices on the network. In addition, this type of setup will also create a Double NAT error.
This might work with some routers and not others. If you were able to use the Guest Network with the Home Hub devices, they allowed this. The Zoom device likely will not.
If the Guest Network function is important to you, you might want to look at a simple modem....not a gateway device.
Thank you Bob, I had a feeling that this might be the case. I have seen this sort of thing mentioned on other similar threads.
Can anyone give me some examples of makes and models which qualify as a "simple modem" that will allow an AEBS to have a guest network? No one seems to have mentioned any particular examples anywhere of what constitutes these devices.
Also Bob, I can access my X5 via my browser and it has various setup options. At the moment, its protocol is PPPoE, which was the default setting, but it can be changed to PPPoA, 1483 bridged (pure bridged mode), 1483 bridged IP and NAT or 1483 routed IP. Would changing to any of these allow me to configure the AEBS as the "main" router?
The X5 is purely a wired ADSL modem and 4 port router - no wireless facility - and the AEBS is the only device connected to it by ethernet cable and is the only one that will be. All computers and mobile devices connect via the AEBS wireless network.
Any advice appreciated.
I suppose that you could try to disable NAT on the X5, but that does not make it a simple modem....and you would still have two DHCP servers on the network....which may be being picked up by the AEBS as a conflict, so it won't likely allow the Guest Network feature to be enabled.
You might want to check with X5 support to see if it is possible to configure the X5 gateway as a simple "bridge mode" modem. That would allow the AEBS to provide DHCP and NAT for the network correctly, which would enable the Guest Network option.
I got a very quick response to a query to Zoom's online support and as long as I switch to the 1483 bridged (pure bridged mode) and enter the VPI value to 0 and VCI value to 38, then the X5 becomes a simple modem and the AEBS can be set to function as my "main" router without a NAT conflict. I can then set up my guest network.
I hope this helps anyone who is having the same problem setting up a guest network on AEBS and needs something that will function as a basic modem. The Zoom X5 was reasonably priced and is very easy to set up and use and is more reliable than the BT Home Hubs we tried before and works beautifully with the AEBS, both as a router and as a simple modem.
I was impressed with the speed of the online support from Zoom and the fact that the person helping me spoke to me in language I could understand and didn't blind me with science. I was taken through each step in turn.
Thank you again, Bob, for pointing me in the right direction.