Using 5GHz and 2.4GHz at the same time?

Hello all! I have an Archer C7 V2 which uses the Qualcomm Atheros QCA9558 ver 1 rev 0.

I have recently upgraded to the OpenWRT SFE fork, primarily since it uses an updated kernel. Side note - this upgrade immediately increased the speedtest results over my WiFi from 9mbps to 50mbps.

I have both the 5ghz and 2.4ghz radios connecting to my service provider's wireless router, since their router broadcasts both. This is where things get interesting...

When I have JUST the 5ghz OR the 2.4ghz radio connected, (so only one is actively connected) then I can send pings from the active interface on the router successfully (ping -I ). So I know the config for these are individually correct.

But when I have BOTH the 5ghz AND the 2.4ghz radio's connected, (so both are actively connected at the same time) then only the ping sent from the 5ghz radio succeeds, the other interface has 100% loss.

I am broadcasting my own SSIDs from the OpenWRT router as the LAN and DMZ, with both connections to my ISP router in the WAN.

My goal would be to have the router use both the 5ghz and 2.4ghz at the same time and effectively share the bandwidth between both connections. Initially I went through the process of configuring mwan3, but it cannot activate both interfaces at the same time due to the problem I've described above.

I've tried all 3 different package versions available of the firmware for this chipset. In older versions of OpenWRT this issue did not exist, but I reset all settings so I'm concerned I've overlooked a setting which will resolve this.

Thanks in advance!

the right way is to use one radio as client, sta and the other radio for AP

Thanks! There's some routers that don't have two radios, so it's clearly possible to use a single radio as both client and AP. I've confirmed it by disabling the 5ghz radio and using the 2.4 as both simultaneously.

Regardless of how "right" it is, it's a setup that will work. And was working in previous versions. But now something's changed. And I'm hoping it's just a setting and not a new driver bug.

So using a dev build from this past weekend with the default (non ct) firmware for ath10k I can get this "mostly" working with mwan3.

The 5ghz and 2.4ghz radios are setup in mwan3 and when I cut off the 5ghz from the source router that openwrt connects to as a client, the 2.4 continues just fine. All clients are connected to a local 2.4 ssid on the router. But when I disable the 2.4 radio on the source router it's not an immediate failover. There's a lot off packet loss immediately for awhile and sometimes all clients connected to 2.4 disconnect and reconnect. At that point traffic is being routed properly out the 5ghz radio, but the ping times are all over the place. I expect perhaps I have some mwan3 config settings wrong. I've tried setting it to flush the conntrack at disconnect / reconnect / ifup / ifdown, but so far no solution to that.

So, it's "working", just these glitches left to resolve. Any advice would be appreciated.

5 GHz is going to be so much faster than 2.4 there's little advantage in trying to combine them. This is something that looks good in ad copy but has no practical use.

Load balancing (mwan3) is best for links of equal speed. True bonding requires the protocol be implemented at both ends, and usually demands the links be equal speed.


Thank you greatly for taking the time to reply! :slight_smile:

My ISP is currently only providing 50mbps so my 5ghz radio isn't really providing much of an improvement from my 2.4ghz.

Two things lead me to want this setup... the 2.4ghz band is usually very busy and is prone to interruptions... and OpenWRT is known for randomly disconnecting from it's WAN client connections on my router (Archer C7 V2). By having mwan3 setup for these, if either of the radios gets interrupted, then internet connectivity for all my devices can continue on the other radio while the connection with the lost radio is reestablished.

I hope that all makes sense.

It's literally "almost" working, I just need some help tweaking the settings to work out the kinks.

If you connect to both bands at the same time, and both interfaces are bridged on each end, then you are creating a loop, where packets go forward and backwards endlessly.


The interfaces aren't bridged, they are members of the mwan3 load balancer and are both in the wan zone

C7 v7 2.4GHz OpenWRT radio driver is buggy since 18.xx. It is buggy in worst possible way: it works until heavy load is present or butterfly farts or something else. Many people with slow connections (and no internal LAN transfers) believe it works fine ... which is does if you only have one laptop and ADSL. But do iperf3 from two clients to wired server and it will go down.

So I recommend to disable 2.4 and only use 5GHz. It is better in every way. Faster, better modulation, less crosstalk etc.