Occasional oscillating ping times that disappear on restart

Question

I'd like help on how to fix long ping times which occasionally (at least once a week) appear on my Mac. To illustrate I've made a plot of ping times I've collected before and after restarting the computer.

At the left here there is a baseline of pings between about 10-30ms and then the problem appears with erratic oscillating ping times as much as 350ms. Then I restart the computer and it goes back to a baseline. I just happened to catch it starting in the above plot, but usually I only start collecting pings after I notice internet delays.

I've looked at other posts on oscillating ping times but they either involve software I don't use or a different type of problem.

I'd like to know how to isolate the source of this problem or a way to fix it without having to restart my computer all the time. I'm connecting via wifi and running Mac OS 13.2.1 on a MacAir M1, 2020.

By the way, I collect the ping data by pasting this into Terminal and then plotting the result:

while :; do
ping -c $((2*60)) 8.8.8.8 | while read line; do
echo $(date): $(sed -n -E 's/.*time=(.*) ms/\1/p' <<<$line)
done
sleep $((0))
done

Update: After 6 days the problem happened again and I did the following (as advised by @nohillside in the comments):

ran my usual test pinging 8.8.8.8 (see script used above)
ran the same test pinging 1.1.1.1
ran traceroute 1.1.1.1 (I did this twice)
I then pinged the 2nd and 3rd addresses from traceroute

The results for both (1) and (2) involved long ping times every 14s or so -- this is the pattern I most commonly see when the problem is occurring. To make this clearer, I've provided a plot of the output from (2) followed by a listing of some of the data:

Time    Ping (ms)
3/13/2023 19:26:42  25.084
3/13/2023 19:26:43  28.201
3/13/2023 19:26:44  16.748
3/13/2023 19:26:45  24.17
3/13/2023 19:26:46  15.163
3/13/2023 19:26:47  14.621
3/13/2023 19:26:48  14.437
3/13/2023 19:26:49  210.239
3/13/2023 19:26:50  70.709
3/13/2023 19:26:51  99.69
3/13/2023 19:26:52  16.017
3/13/2023 19:26:53  22.365
3/13/2023 19:26:54  22.405
3/13/2023 19:26:55  22.227
3/13/2023 19:26:56  22.233
3/13/2023 19:26:57  21.61
3/13/2023 19:26:58  16.033
3/13/2023 19:26:59  22.233
3/13/2023 19:27:00  22.476
3/13/2023 19:27:01  17.68
3/13/2023 19:27:02  21.989
3/13/2023 19:27:03  18.368
3/13/2023 19:27:04  15.418
3/13/2023 19:27:05  48.894
3/13/2023 19:27:06  15.997
3/13/2023 19:27:07  22.298
3/13/2023 19:27:08  14.297
3/13/2023 19:27:09  22.053
3/13/2023 19:27:10  26.052
3/13/2023 19:27:11  21.178
3/13/2023 19:27:12  19.809
3/13/2023 19:27:13  13.789
3/13/2023 19:27:14  21.83
3/13/2023 19:27:15  16.125
3/13/2023 19:27:16  14.739
3/13/2023 19:27:17  13.904
3/13/2023 19:27:18  149.047
3/13/2023 19:27:19  19.017
3/13/2023 19:27:20  62.321
3/13/2023 19:27:21  25.906
3/13/2023 19:27:22  24.919

(3) I ran traceroute 1.1.1.1 twice and the results were significantly different for the 2nd and 3rd addresses as you can see below:

tony@mba Desktop % traceroute 1.1.1.1
traceroute to 1.1.1.1 (1.1.1.1), 64 hops max, 52 byte packets
 1  192.168.1.254 (192.168.1.254)  12.215 ms  5.103 ms  2.341 ms
 2  station15.multimania.isdnet.net (194.149.174.112)  15.909 ms  15.198 ms  13.144 ms
 3  station3.multimania.isdnet.net (194.149.174.100)  12.622 ms  12.972 ms  13.759 ms
 4  prs-b3-link.ip.twelve99.net (62.115.46.68)  13.092 ms  13.989 ms  13.195 ms
 5  prs-bb2-link.ip.twelve99.net (62.115.118.62)  12.937 ms
    prs-bb1-link.ip.twelve99.net (62.115.118.58)  13.850 ms  14.015 ms
 6  prs-b1-link.ip.twelve99.net (62.115.125.171)  14.284 ms  14.801 ms
    prs-b1-link.ip.twelve99.net (62.115.125.167)  13.884 ms
 7  cloudflare-ic363840-prs-b1.ip.twelve99-cust.net (213.248.73.69)  48.903 ms  13.638 ms  14.091 ms
 8  172.71.120.2 (172.71.120.2)  15.664 ms
    141.101.67.52 (141.101.67.52)  14.133 ms
    172.71.124.2 (172.71.124.2)  13.672 ms
 9  one.one.one.one (1.1.1.1)  13.506 ms  14.465 ms  13.128 ms
tony@mba Desktop % traceroute 1.1.1.1
traceroute to 1.1.1.1 (1.1.1.1), 64 hops max, 52 byte packets
 1  192.168.1.254 (192.168.1.254)  23.002 ms  4.272 ms  8.572 ms
 2  station15.multimania.isdnet.net (194.149.174.112)  259.673 ms  13.850 ms  14.366 ms
 3  station3.multimania.isdnet.net (194.149.174.100)  147.235 ms  15.467 ms  59.656 ms
 4  prs-b3-link.ip.twelve99.net (62.115.46.68)  20.804 ms  15.044 ms  13.156 ms
 5  prs-bb1-link.ip.twelve99.net (62.115.118.58)  15.311 ms
    prs-bb2-link.ip.twelve99.net (62.115.118.62)  14.601 ms  15.301 ms
 6  prs-b1-link.ip.twelve99.net (62.115.125.167)  14.514 ms  13.935 ms
    prs-b1-link.ip.twelve99.net (62.115.125.171)  16.275 ms
 7  cloudflare-ic363840-prs-b1.ip.twelve99-cust.net (213.248.73.69)  30.162 ms  45.160 ms  15.904 ms
 8  172.71.124.2 (172.71.124.2)  15.765 ms  15.259 ms
    141.101.67.52 (141.101.67.52)  15.232 ms
 9  one.one.one.one (1.1.1.1)  16.242 ms  15.110 ms  13.432 ms

The result of pinging the 3rd and 2nd addresses was:

tony@mba Desktop % ping 194.149.174.100
PING 194.149.174.100 (194.149.174.100): 56 data bytes
64 bytes from 194.149.174.100: icmp_seq=0 ttl=254 time=22.169 ms
64 bytes from 194.149.174.100: icmp_seq=1 ttl=254 time=26.749 ms
64 bytes from 194.149.174.100: icmp_seq=2 ttl=254 time=33.288 ms
64 bytes from 194.149.174.100: icmp_seq=3 ttl=254 time=67.996 ms
64 bytes from 194.149.174.100: icmp_seq=4 ttl=254 time=211.063 ms
64 bytes from 194.149.174.100: icmp_seq=5 ttl=254 time=22.132 ms
64 bytes from 194.149.174.100: icmp_seq=6 ttl=254 time=25.550 ms
64 bytes from 194.149.174.100: icmp_seq=7 ttl=254 time=23.739 ms
64 bytes from 194.149.174.100: icmp_seq=8 ttl=254 time=21.695 ms
64 bytes from 194.149.174.100: icmp_seq=9 ttl=254 time=21.745 ms
64 bytes from 194.149.174.100: icmp_seq=10 ttl=254 time=22.897 ms
64 bytes from 194.149.174.100: icmp_seq=11 ttl=254 time=24.286 ms
64 bytes from 194.149.174.100: icmp_seq=12 ttl=254 time=15.421 ms
64 bytes from 194.149.174.100: icmp_seq=13 ttl=254 time=24.192 ms
64 bytes from 194.149.174.100: icmp_seq=14 ttl=254 time=21.230 ms
64 bytes from 194.149.174.100: icmp_seq=15 ttl=254 time=24.187 ms
64 bytes from 194.149.174.100: icmp_seq=16 ttl=254 time=55.852 ms
64 bytes from 194.149.174.100: icmp_seq=17 ttl=254 time=86.073 ms
64 bytes from 194.149.174.100: icmp_seq=18 ttl=254 time=120.424 ms
64 bytes from 194.149.174.100: icmp_seq=19 ttl=254 time=23.754 ms
64 bytes from 194.149.174.100: icmp_seq=20 ttl=254 time=19.169 ms
64 bytes from 194.149.174.100: icmp_seq=21 ttl=254 time=21.715 ms
64 bytes from 194.149.174.100: icmp_seq=22 ttl=254 time=22.366 ms
64 bytes from 194.149.174.100: icmp_seq=23 ttl=254 time=14.963 ms
64 bytes from 194.149.174.100: icmp_seq=24 ttl=254 time=24.034 ms
64 bytes from 194.149.174.100: icmp_seq=25 ttl=254 time=23.883 ms
64 bytes from 194.149.174.100: icmp_seq=26 ttl=254 time=23.408 ms
^C
--- 194.149.174.100 ping statistics ---
27 packets transmitted, 27 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 14.963/38.666/211.063/41.094 ms
tony@mba Desktop % ping 194.149.174.112
PING 194.149.174.112 (194.149.174.112): 56 data bytes
64 bytes from 194.149.174.112: icmp_seq=0 ttl=254 time=15.971 ms
64 bytes from 194.149.174.112: icmp_seq=1 ttl=254 time=14.559 ms
64 bytes from 194.149.174.112: icmp_seq=2 ttl=254 time=21.226 ms
64 bytes from 194.149.174.112: icmp_seq=3 ttl=254 time=14.878 ms
64 bytes from 194.149.174.112: icmp_seq=4 ttl=254 time=22.699 ms
64 bytes from 194.149.174.112: icmp_seq=5 ttl=254 time=13.368 ms
64 bytes from 194.149.174.112: icmp_seq=6 ttl=254 time=22.720 ms
64 bytes from 194.149.174.112: icmp_seq=7 ttl=254 time=23.050 ms
64 bytes from 194.149.174.112: icmp_seq=8 ttl=254 time=16.302 ms
64 bytes from 194.149.174.112: icmp_seq=9 ttl=254 time=154.690 ms
64 bytes from 194.149.174.112: icmp_seq=10 ttl=254 time=16.087 ms
64 bytes from 194.149.174.112: icmp_seq=11 ttl=254 time=14.639 ms
64 bytes from 194.149.174.112: icmp_seq=12 ttl=254 time=22.354 ms
64 bytes from 194.149.174.112: icmp_seq=13 ttl=254 time=20.438 ms
64 bytes from 194.149.174.112: icmp_seq=14 ttl=254 time=14.141 ms
64 bytes from 194.149.174.112: icmp_seq=15 ttl=254 time=20.786 ms
64 bytes from 194.149.174.112: icmp_seq=16 ttl=254 time=14.219 ms
64 bytes from 194.149.174.112: icmp_seq=17 ttl=254 time=19.854 ms
64 bytes from 194.149.174.112: icmp_seq=18 ttl=254 time=21.329 ms
64 bytes from 194.149.174.112: icmp_seq=19 ttl=254 time=13.578 ms
64 bytes from 194.149.174.112: icmp_seq=20 ttl=254 time=19.821 ms
64 bytes from 194.149.174.112: icmp_seq=21 ttl=254 time=20.707 ms
64 bytes from 194.149.174.112: icmp_seq=22 ttl=254 time=16.926 ms
64 bytes from 194.149.174.112: icmp_seq=23 ttl=254 time=124.691 ms
64 bytes from 194.149.174.112: icmp_seq=24 ttl=254 time=143.539 ms
64 bytes from 194.149.174.112: icmp_seq=25 ttl=254 time=129.282 ms
64 bytes from 194.149.174.112: icmp_seq=26 ttl=254 time=21.577 ms
64 bytes from 194.149.174.112: icmp_seq=27 ttl=254 time=20.901 ms
^C

The trouble with pinging google is you don't know where that's actually going, or whether the latency may be closer to home. — Tetsujin, Mar 06 '23 at 14:11
A key point here is that the problem disappears when the computer is restarted. I don't see how pinging google has anything to do with that. — Tony M, Mar 06 '23 at 14:24
This really should be done in Safe Mode to ensure no 3rd party software is clogging the network with traffic and you should use a proper throughput diagnostic tool like speedtest or iperf3 — Allan, Mar 06 '23 at 14:26
That's the trouble with the 'well it cannot possibly be that' approach. It closes your mind to other possibilities. I'd investigate bufferbloat while you're at it. — Tetsujin, Mar 06 '23 at 14:31
When the problem (oscillating ping times) occurs, can you also try to ping 1.1.1.1? And run traceroute 1.1.1.1 and then ping the IP shown in the 2nd or 3rd line of the output? — nohillside, Mar 06 '23 at 17:56
Thank you @nohillside for responding to my request "how to isolate the source of this problem" in such a concrete way. The problem isn't happening now, but I followed those steps to get a baseline reading. The next time the problem happens I'll do so again. — Tony M, Mar 06 '23 at 19:09
@nohillside I have updated my original post to include the results of the tests you advised me to run. — Tony M, Mar 13 '23 at 19:08
What is the meory usage of your machine when you have the speed issue? — mmmmmm, Mar 13 '23 at 19:30
I'm still having the problem right now and Activity Monitor shows this under the Memory Tab: Physical Memory 16GB, Memory Used: 11.8GB, Cached Files 3.88GB, Swap Used 689MB -- not sure if that's what you want — Tony M, Mar 13 '23 at 19:35
It doesn't quite fit your symptoms, but there've been problems like this in the past due to location services scanning for other WiFi networks. There's some good info & troubleshooting suggestions here. — Gordon Davisson, Mar 13 '23 at 19:42
Thanks for the update, based on the data the cause is locally on your Mac or within your local network. See the link Gordon shared for possible next steps. — nohillside, Mar 14 '23 at 07:19

Occasional oscillating ping times that disappear on restart

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