Very high wifi latency on Asus AC65P

Installing and Using OpenWrt
1

I get extreme spikes in latency on this router and cannot figure out what to configure. When I ping 8.8.8.8 from my laptop i usually get 7ms ping but there are spikes every few seconds to ~100ms. This is when the network is absolutely idle, no downloads whatsoever. Here are some sample tests:

The pings are done every 250ms:

64 bytes from 8.8.8.8: icmp_seq=11718 ttl=120 time=7.23 ms
64 bytes from 8.8.8.8: icmp_seq=11719 ttl=120 time=7.26 ms
64 bytes from 8.8.8.8: icmp_seq=11720 ttl=120 time=7.18 ms
64 bytes from 8.8.8.8: icmp_seq=11721 ttl=120 time=14.9 ms
64 bytes from 8.8.8.8: icmp_seq=11722 ttl=120 time=14.4 ms
64 bytes from 8.8.8.8: icmp_seq=11723 ttl=120 time=110 ms
64 bytes from 8.8.8.8: icmp_seq=11724 ttl=120 time=117 ms
64 bytes from 8.8.8.8: icmp_seq=11725 ttl=120 time=9.63 ms
64 bytes from 8.8.8.8: icmp_seq=11726 ttl=120 time=67.7 ms
64 bytes from 8.8.8.8: icmp_seq=11727 ttl=120 time=121 ms
64 bytes from 8.8.8.8: icmp_seq=11728 ttl=120 time=36.5 ms
64 bytes from 8.8.8.8: icmp_seq=11729 ttl=120 time=7.21 ms
64 bytes from 8.8.8.8: icmp_seq=11730 ttl=120 time=7.69 ms

pings
pings977×621 67.3 KB

The test looks similarly on my phone.

The things I tried to fix this that I found somewhere on the web that seemed to help others (i'm only optimizing 5Ghz):

  1. Changing channels 36, 40, 44, 48
  2. Changing channel width between 40/80
  3. Changed distance optimization to 150m
  4. Changed DTIM interval to 1
  5. Played around with SQM on wan/wan6 interface: I used different download/upload values (including 0), different per packet bytes for Ethernet with overhead (tried 18, 22, 44), and many different algorithm combinations including the default and cake+piece of cake.
  6. I added the bursting and ff options in /etc/config/wireless

Nothing helped even a bit. The only things I noticed are that using ff and busting causes the lags to come more often and using SQM drastically reduces my download speeds (from around 220 to 50-90 depending on settings).

Whats wrong here? Do you have any suggestions?

2

I've the same problem with my Ubiquiti UAP AC LR, but my lag spikes are smaller. I had them even in official firmware.

There are a lot of wifis where you live? Because maybe it's caused by a high congested spectrum.

3

I checked this with some wifi analyser tool and there is only one 5Ghz network nearby and its on channels around 100-110. So its basically empty here.

4

Have you tested running Asus stock firmware (not OpenWRT)?

5

Not for this exactly. The issue arose when I started using streaming from steam on my laptop which I did not do when I bought the router. I will revert to stock in some near future and test for this.

I certainly see worse performance overall on openwrt though (worse reception in rooms further away and worse speeds when doing speedtests).

6

I'm pretty sure it will work better in stock firmware.

7

Yes it is noticably better. I'll stick to stock firmware for now.