Is my guest network set up wrong? Or do I just misunderstand it?

[MonkeyK]

I was recently playing around with the mobile app fing. I had an old cell phone on my guest network and scanned it.
I was surprised to see a listing of all devices on my main network as well as guest network devices. How can that be? I would have thought that the guest network would be separate and unable to see devices on the main network.
Do I just have the wrong idea? If so, what protection does the guest network really offer?

My router is an Asus rt-n66u and is currently set up with three networks:
Main: secured with a strong password. For all computers in the house, with access to our nas, and printer
Guest: secured with a easy to enter password. Just Internet access
Iot: secured with a strong password. For devices that I don't know anything about. Just Internet access.

 

[ColinTaylor]

Do you have "Access Intranet" disabled in your Guest Network setup?

 

[MonkeyK]

I don't recall that as an option. I'll check when I get home tonight

 

[ColinTaylor]

Sometimes people misread that option as "Access Internet" and change it to enabled by mistake.

 

[MonkeyK]

Wow. What an oversight on my part! Thank you for pointing that out!
That said, I updated the "Access Intranet" setting, the router restarted and I rescanned.
Now it looks like
IoT: shows about 5 devices, including the router and the phone that I am using to scan.
Guest: shows all devices from IoT + a few from guest
Main: shows all devices from guest + a few from main

I can live with this, but it still doesn't seem right that one guest network sees all devices in another

 

[fax]

Try to clean the cache from the PC or device you use to scan the LAN.
Sometime what you see is just the cache of previous session(s).

 

[MonkeyK]

Yup. that was it. Funny how my iPhone doesn't have an option to clear the app's data, but my daughters old Android does.

 

[fax]

I am glad to hear you sorted it out!

 

[BreakingDad]

Yup. that was it. Funny how my iPhone doesn't have an option to clear the app's data, but my daughters old Android does.

Android > Apple

 

[jtjbt20x]

Here's how to flush your iPhone's DNS cache:

http://osxdaily.com/2015/03/31/clear-dns-cache-ios/

 

[chris2kari]

Yup. that was it. Funny how my iPhone doesn't have an option to clear the app's data, but my daughters old Android does.

Yes it does.

Go to "Settings", "Safari" & choose the option to clear web site data.