Mysterious periodic packet loss on 2nd ASUS in a row

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MaxMotovilov

New Around Here
Looked at everything I could think of and am at my wits' end... This is what it looks like:

11:00 PM> 231........2..23............32............231...........23............33............32.22.........422..........
11:10 PM> ......42.......2...242............23.1..........231...........231...........23............33............322..32
11:20 PM> ............33............33............33............32........2...23............32............23.............
11:30 PM> ....33............33............33............32............33............411...........411...........411......
11:40 PM> ..........33............33............32............23.1..........42............42............42............4..
11:50 PM> .123............33............33............33............32............231...........23.1..........42.........
12:00 AM> ........42............411...........42............42............42............24............231...........231..
12:10 AM> 23............33............33............32............42............42............42............42...........
12:20 AM> ......23............32............231...........23............33............32............32............43...32
12:30 AM> ............33............32............23............32............23............32............23.1...........
12:40 AM> ....42............43............33............343...........32............411...........41............33.......
12:50 AM> ..........32............42............42............42............42............41............32............4..


and so on forever: every dot is ten pings to the nearest hop (i.e. the gateway assigned by the ISP's DHCP), number is "replies lost out of 10". Ping was running on a router -- running it on a box inside the LAN does the same exact thing, synchronized. So about 25% loss coming up every 70 seconds or so. Now, what it isn't:
  • ISP issues: I connect my Linux box to the modem directly -- nothing like this happens
  • Bad firmware: long history -- first the issue came up on an RT-AC68U couple months ago. I have tried both Merlin and Asus f/w, different versions - nothing helped. Finally I bought a brand new ZenWiFi AX (currently at 3.0.0.4.386_43181-g6099e58) and retired the AC68U to the duties of an AiMesh node upstairs (currently running 3.0.0.4.386_43129-g60defb2). The problem went away and I breathed easily. AND NOW IT'S BACK!
  • Running OOM - nope
    Mem: 290644K used, 219520K free, 1540K shrd, 16616K buff, 50696K cached
  • Running low on file space - nope
    /dev/root 53632 53632 0 100% /
    devtmpfs 254976 0 254976 0% /dev
    tmpfs 255080 188 254892 0% /var
    tmpfs 255080 1136 253944 0% /tmp/mnt
    ubi1:data 4584 80 4232 2% /data
    tmpfs 255080 1136 253944 0% /tmp/mnt
    tmpfs 255080 1136 253944 0% /tmp
    /dev/mtdblock9 48128 3540 44588 7% /jffs
  • Running hot - not visibly so; couldn't find the temp gauge in the current f/w UI but here's this:
    # cat /sys/class/thermal/thermal_zone0/temp
    68493
  • Logs - nothing whatsoever of interest in dmesg, /var/log or /jffs. Certainly nothing that would come up with that sort of period.
  • Top activity - nothing correlates.
I am about to change the ISP, partially out of sheer desperation, partially because of a good plan/rate. Will know how it goes there, but suspect it won't be good. Any ideas at all??? Anywhere in the system I haven't looked?

Thanks in advance,
...Max...
 
Last edited:

ColinTaylor

Part of the Furniture
So if you ping 8.8.8.8 instead of your ISP gateway do you get the same packet loss?
 

MaxMotovilov

New Around Here
Anything at all - I ended up pinging the next hop as my litmus test because it was simpler. I originally started off diagnosing issues w/my work VPN and MyTraceroute was showing nearly identical loss on all hops. But to answer your question - yes, public DNS, public Web endpoints - all exhibit the same periodic loss: 10:03 AM> ....41...........131.... (this is now w/8.8.8.8 - I ran out of patience). The biggest pain it causes with conference calls - my stream goes away for a few seconds during these periods.
 

ColinTaylor

Part of the Furniture
You could try logging into the router and running top. You might get lucky and see some process spiking at the time the packet loss occurs.
 

MaxMotovilov

New Around Here
Oh, I've done that - see my original post. Nothing. There are some periodically activating processes (e.g. watchdog) but they do so well out of phase/frequency (i.e. uncorrelated) with the packet loss.
 

MaxMotovilov

New Around Here
I didn't mention that on first occurrence of this I got Spectrum tech to come out and measure the signal -- all in tip top shape. That was when I first tried excluding the router from the test and connecting to my Linux desktop directly... which led to replacing the still new-ish router with the latest and greatest.

Note that the problem was NOT there a month ago when I unpacked and set up the ZenWiFi. It also was not there for those few days I put into service my ages old "white knight" Asus router I keep as a spare. It feels like a cumulative issue of some sort, but what can it be???
 
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