large downloads flood my Asus AC68U

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Regular Contributor
I've got a 500mbit synchronous fibre link that delivers what it's supposed to, and my download speeds (on sites that support it) maximise my links ability. So far so good.

I've got CAT-6 & gigabit switches in the house, and my main computer is wired. If I start a long-running download on my computer, the entire family notices that internet speeds completely die on their wireless devices. I suspect that the AC68U hardware is the culprit: that it just cannot handle the traffic throughput. Can anyone confirm?

Thinking of getting a new ax router, but don't wan't to have the same problem, so not decided yet if I should go back to pfSense on their dedicated hardware and just buy an ax AP. Any suggestions for an Asus ax router that doesn't have problems with throughput saturation?


New Around Here
If your download is a BitTorrent that is pulling from several different users, it can happen. Hardwired devices tend to have a priority over wireless connections because the ASUS is more of an unmanaged switch. Try turning on MIMO in the professional settings of your wireless tab. It might help a little. Other option is to turn on QOS but your mileage will vary as this can sometimes turn off CTF (Cut through forwarding) under NAT acceleration; slowing down or causing your hardwired connections to not capitalize on the full throughput of your modem. Basically NAT acceleration with Cut through forwarding allows hardwired connections to pass on data directly and “cut through forwarding” to a specific Ethernet port bypassing all together the forwarding pathway the routing information tables that ASUS uses to direct network traffic wirelessly. This feature, when off, will keep the wireless devices from dropping their internet connectivity but at the same time
subject your hardwired connections to the speed limitations of the hardware resources available used in directing traffic.


Regular Contributor
It wasn't BitTorrent, it was Steam game updates that maxed out my d/l speeds. But I've also had it happen when grabbing several large files (5-10GB) from works ftp server. I couldnt find any MIMO option in the Professional tab? I do have CTF enabled, so i'll play around with that and see if wireless is better when it's turned off. Thanks for the tips. I'm mostly using 5GHz channel on all my wireless devices, but they sometimes have an undesireable tendency to switch over to 2.4GHz, as for some reason my 5GHz radio gets itself in a twist every now and again. I put this down to a hardware issue with this model of wireless router.


Regular Contributor
You could try installing FlexQOS, it might give you the control you're looking for.


Senior Member
What version of firmware are you running? You twigged my interest when you mentioned Steam downloads. I was having a slightly different issue with Steam downloads messing up VoIP phone calls. The culprit seems to be new adaptive QoS categories Asus created. VoIP traffic and Steam downloads are the same priority and are lumped in together in the work-from-home QoS category. Dave suggested watching the classification report while passing each type of traffic to see which category it falls in. Certainly was revealing. Flexqos is said to be an option, so is rolling back to the firmware from late last year before Asus invented these silly "covidized" QoS categories like work or learn from home.

Basically you can't have work from home as your selected QoS type or have it as the highest category in the custom list. I am going to try Dave's Flexqos but if it does not work out I will have to find a router where VoIP can be the highest priority of all. Asus was good until they made this poor decision.


Regular Contributor
I'm on 384.14. I did not think that I needed to have QoS when I had such a fat link. I thought QoS was only really helpful if link speed was a problem so that you had to manage what certain devices had access to? Anyway, when I did a new Steam update yesterday and it wanted to drag down a 1.7GB update, I could see in the Asus router status page that CPU core 1 went up to 97%, so I suppose that there is that factor as well, that the traffic throughput puts substantial load on the CPU, and that if I had a faster CPU in the router, I would probably notice it a lot less.

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