Guest Networks, bit of a deadline

[iomatic]

Hey all, maybe you have insight here. Airport network, extended with a bunch of little Express units work fine, has been working in another house (and now in a new one) for several years. Enabling a Guest Network, not so much.

My config:
Xfinity Cable modem -->
Apple Extreme Base Station, uses a DHCP IP, and DHCP/NAT enabled. Guest Network enabled.

According to Airport Utility, all are connecting to the Base Station directly
--> Express
--> Express
--> Express, upstairs, above garage (this is where I want to extend a Guest Network)

The problem is I can't extend the guest network because none of the Express units "see" the Guest Network to extend (just the existing one). Would love to get this going right before guests arrive in 2 days!

Any thoughts here? Am I going to have to figure out how to manage the Xfinity modem (really? Pointers here if you got it; it's been awhile). So very grateful for help here.

Thanks!!!
[doublepost=1516830607][/doublepost]So is this it? Set the xfinity modem to be just a modem and not provide DHCP/nat?

Anyone remember how to setup the modem that way and speak to if this will work/not work, or leaving me stranded resetting everything to default and reconfiguring (ask me how I know)?

Tia!

 

[techwarrior]

From the sound of it, you are wireless extending with the 3 Expresses, not hardwired to the LAN?

Guest WiFi uses a different subnet (172.x.x.x vs 192.168.x.x), the guest WiFi is not routable to the Extreme. I have seen articles suggesting wireless uplinks on airports do not support guest traffic. My Expresses are hardwired and enabling Guest on them fails to route to the internet. So, my take is Airport only supports Guest on the router (Extreme in your case).

I suspect it has to do with VLANs (Virtual LANs). VLANs isolate hosts on different subnets to reduce chatter, but without requiring additional hardware. While routing can be enabled between VLANs on more sophisticated network gear, Apple tries to keep things simple in the Airport line, so the two VLANs are isolated with the router managing NAT for two networks, but not allowing traffic between the networks. A guest network is intentionally not routable to the home network, for security reasons.

I suspect it is laziness or oversight that Apple didn't disable to option for Guest on Airports that are in Bridge mode (NAT disabled).

An alternative if you are not concerned with guests seeing the other computers on your network (but don't want them to know your WiFi password) would be to hardwire one of the Expresses to the Extreme. If running ethernet to the garage is impractical, use Powerline adapters to send the Ethernet signal over your home's power lines to the garage. Plug one adapter into a LAN port on your router, then the other in the garage with an ethernet cable to the Wan port on the Express.

On that Express, on the Network tab, set the Router to Off (Bridge Mode) and on the Wireless tab Network Mode = Create a Wireless Network. Use a WiFi SSID (Wireless Network Name) and password that is different than your main WiFi. You can call it anything you want, Guest for instance, but don't configure it as a Guest Wireless Network. As long as your file sharing is setup properly so only authenticated users can access files on your computers or network drives, your guests may see your computers, but not be able to access them. They will also see and be able to use things like AppleTV, Airplay devices, etc that are connected to your home network\WiFi.

I am curious what your WiFi speeds are. Apple suggests wireless extended networks should never use more than one satellite Access Point (Expresses in your case). The reason is the one radio is sharing uplink and client connections, effectively cutting throughput in half. Having 3 wirelessly connected Access Points would seem to kill WiFi on the Extreme.

BTW, if you suffer from slow WiFi, and choose to go the Powerline Adapter route, you can buy 4 adapters, plug one in near the router, and one near each of the Expresses. That would give all of your expresses a 100Mbps uplink over ethernet (restricted by the Wan port speed on Expresses).
[doublepost=1516843483][/doublepost]One more piece. That linked article is a bit off. In your case, I think you said you have a Comcast modem, but not router? So, the modem is just that, a modem, not a router. So, I do't think that is your issue. The issue is, guest is not supported on anything but the main router in an airport network.