2.4 GHz routing and network discovery

[BenJuan26]

Devices connected to the 2.4 GHz network can't connect directly to other devices on 2.4 GHz. This includes servers, such as my Raspberry Pi running the Fluidd 3D printer frontend, as well as my Roku (which I have since switched to 5 GHz and now it works).

I keep my phone connected to 2.4 GHz because I want the range and I don't need the speeds of the other bands. I am not interested in whole home internet or band steering; I have tried them, and I never have anything but problems. My phone can see my NAS just fine, no matter which band I'm connected to. The NAS is connected via Ethernet. My Raspberry Pi is connected to 2.4 GHz because it's on the other side of the house. It is well within the range of that band, and throughput is sufficient. When I want to talk to my 3D printer, I have to switch my phone over to 5 GHz. I should not have to do this. No matter which band is being used, they are all connecting to the same network, and routing should be available.

I did an additional test and set up a web server on my laptop. When connected to the 5 GHz network, I was able to see it from the 2.4 GHz on my phone, but not when the laptop was connected to 2.4 GHz. The same goes for my Roku: when it was connected via 2.4 GHz, my phone couldn't see it unless I switch to 5 GHz. I switched the Roku to 5 GHz, and my phone was able to see it from 2.4 GHz. So the issue appears to just be from 2.4 GHz devices to other 2.4 GHz devices.

If this is a deliberate limitation, it's a silly one, and if it's inadvertent, please fix it.

[BellPatricia · Accepted solution]

Hi @BenJuan26,
Welcome to the Bell Community, and thanks very much for reaching out.

Are any of your devices connected to a guest network?

Can you test further to see if you are able to successfully ping each device that is connected to the 2.4GHz network? Simply access your modem GUI (192.168.2.1) select Advanced Tools and Settings, then under the Tools section click Utilities.

Hope to hear back from you,

- Patricia
 

[BenJuan26]

Hi @BellPatricia,

Thanks for looking into this. I have no devices connected to a guest network. From the modem, I can ping both the Raspberry Pi as well as my Pixel 7 phone, both of which are connected to the 2.4 GHz network. 0% packet loss, even with 20 packets sent.

After doing both of those pings, I tried pinging the phone from the Pi, and it was also successful, surprisingly. Then I checked, and my phone was able to access the Pi's web server, strangely enough. This reminds me of behaviour that I noticed previously during testing:

1. Try to access the Pi from my phone on 2.4 GHz, unsuccessfully.
2. Switch to 5 GHz and try again. Success.
3. Switch back to 2.4 GHz. This time connections work, even after clearing cache (though admittedly not DNS cache... not sure that's relevant since this is through the IP directly).
4. Try again on 2.4 GHz some time later, and it doesn't work again.

I am curious whether doing the pings triggered whatever mechanism I was experiencing in the above scenario. I will try 2.4 GHz from my phone again after some time has passed, and see whether the behaviour returns. If it doesn't, this is mysteriously solved.

[BenJuan26]

Hello again @BellPatricia,

Simply pinging the 2.4 GHz devices resolved the issue for quite a while. However, I recently changed some settings around (such as disabling UPnP and updating some port forwarding rules) and rebooted the modem a few times between changes. Now, I'm seeing the same problems I was seeing before. Pinging from the modem didn't help this time. The pings were successful to each device, but 2.4 GHz devices cannot see other 2.4 GHz devices, again.

[BellPatricia]

Good afternoon @BenJuan26,

Thank you for keeping in touch with the Bell Community 🙂

Can you clarify if you only disabled UPnP and updated some port forwarding rules? If you made any other changes please let us know what they were. Perhaps that can help us determine the cause. To test further on your side you could also try changing one setting at a time to see if you can pin point when the issue starts.

Looking forward to your reply.

- Patricia

[BenJuan26]

Those were the only changes I made, and I have since re-enabled UPnP. I think the restart alone is what set it back to the initial state where these connections don't work. I still haven't been able to make them work again. It's hard for me to know how the problem was solved before, because all I did was use the modem's ping utility on each device, and suddenly it worked. This time, the pings are still successful from the modem, but it doesn't change the lack of connection between devices connected through 2.4 GHz. Is there some sort of verbose logging I can enable to see what the router sees when the devices initiate the requests? Or is there a utility I could use on Android, Linux, or Windows that could give some insight?

[BenJuan26 · Accepted solution]

Small update: I have changed nothing, no router pings or restarts, and suddenly it's working again. I can see my Raspberry Pi on 2.4 GHz from my phone on 2.4 GHz. I wish I had more information as to why this is happening. Again, if there is any sort of logging or dumping I can do to get a sense of the switching logic when this inevitably stops working again, that would really help me.