Hi
Ive got my wifi router up and running with OpenWrt. Only issue is I haven’t been able to add a second wifi client. I can get the wireless working on the 5Ghz but unable to add a second wifi 2.4GHz.
Thanks
Andrew
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Hey Andrew,
The CM4 uses the same hardware that’s on a regular RPi 4, so this answer I found on google will apply to your situation:
Can RPi4 run simultaneously on dual band (WiFi 2.4GHz / 5GHz)? - Raspberry Pi Stack Exchange.
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Thanks Oliver,
I had a little read but don’t quite understand what they are on about. I’ll do some more googling and see if I can find something similar with better instructions
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The 4th post in the link @Oliver posted says it all I think.
On the Raspberry Pi 4, wireless support is provided by the same Cypress CYW43455 chip as on the Pi 3 B+. A limitation of this chip is that it cannot do Real Simultaneous Dual Band (RSDB). You could add a USB wifi module, to have two devices, each on a different band.
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The summary is that in general you can’t connect to 2.4GHz and 5GHz at the same time.
There are some specific cases where you can get it to work, but they are very specific cases and the configuration is far from user friendly - you’ll need to do quite a bit of work and learn a lot about WiFi to be able to implement it.
If I understand correctly you’re trying to setup a Wireless Access Point (WAP) on both 2.4GHz and 5GHz? I imagine you want it to just work like an off the shelf dual band router. The only way you’ll be able to do this and have it work with pretty much any WiFi device will be to get another WiFi chip. A USB WiFi Dongle will probably be the way to go. Use the built-in WiFi for 5GHz, and that way you can get a cheap 2.4GHz WiFi dongle.
Something with a proper antenna like this (though this one has been retired and is no longer available):
In theory you can bridge the two networks, though I found this topic on the OpenWRT forums that indicates it might not be so straight forward:
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Thanks Oliver. Yes thats correct, but more importantly I need 2.4 more than 5. Maybe I can change the radio to work on 2.4ghz and be done with it. Little bit disappointed, maybe I should have bought an off the shelf wifi router. Actually I’ll buy that dongle and see if I can get that to work. Thanks again for your help.
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Hi Andrew,
Let us know how you go with the dongle option or if there are any further issues, I’m sure others sooner or later will be trying to do exactly the same thing and will want to know if the workaround got you both bands.
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Any other recommendations? The dongle option is out of stock
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Hi Andrew,
The one that is out of stock is the only dongle we have with a built in antenna. We have others on the site which are otherwise all very similar.
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Hi Andrew,
Yes, as I mentioned that one’s actually been retired (ie. discontinued). I was just using it as an example of what you could look for since we don’t have another in our range with a full sized antenna at the moment.
The search link @Trent5487676 provided should return pretty much everything we have, but for a router you need quite strong signal, so I’d recommend a USB dongle with a full sized antenna.
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I tried a USB antenna but could get it to work. That’s fine. I just changed the on board one to 2.4Ghz as that the main frequency that my devices use. I have also connected an external antenna but the signal strength is still not as good as my Huawei. Any tips on improving the signal strength?
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Hi Andrew,
Radio (and especially WiFi) is a tricky problem to solve. I’d look into standalone access points to supplement your router. If you go down the Unifi route (most affordable enterprise gear that anyone can set up), you can even use a Pi as a “controller” for the network to host the webUI and issue commands to access points. Alternatively, Searching eBay for used enterprise gear is another valid way to pick up things cheaper.
Or, just try setting up your Huawei as an access point only, rather than a modem/router/AP.
-James
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Hi James,
I might try a Unifi AP. Will this work with the Openwrt router without too much configuration?
Regards
Andrew
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Just enabled the external antenna. Didnt know I had to do this. Has made a massive difference.
Edited the config.txt and added dtparam=ant2
Getting normal wifi range now.
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Ah nice, good find! I’m still learning some of the tricks to CM4s too 
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I’ve ditched the project. I bought a Unifi AP Pro and it works awesome. Going sell the router on ebay if anyone is interested.
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