Strange delay for every 10th ping

[Chris Green]

Can anyone suggest why I should see this delay on every 10th ping
across my home LAN:-

    chris$ ping dns
    PING dns (192.168.1.2) 56(84) bytes of data.
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=1 ttl=64 time=3.95 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=2 ttl=64 time=5.38 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=3 ttl=64 time=5.39 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=4 ttl=64 time=4.59 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=5 ttl=64 time=4.59 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=6 ttl=64 time=4.58 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=7 ttl=64 time=4.33 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=8 ttl=64 time=4.12 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=9 ttl=64 time=4.15 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=10 ttl=64 time=3.92 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=12 ttl=64 time=112 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=13 ttl=64 time=5.39 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=14 ttl=64 time=5.35 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=15 ttl=64 time=5.42 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=16 ttl=64 time=7.05 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=17 ttl=64 time=4.52 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=18 ttl=64 time=4.47 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=19 ttl=64 time=4.28 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=20 ttl=64 time=4.09 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=22 ttl=64 time=112 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=23 ttl=64 time=5.36 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=24 ttl=64 time=5.59 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=25 ttl=64 time=6.51 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=26 ttl=64 time=5.68 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=27 ttl=64 time=4.63 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=28 ttl=64 time=4.52 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=29 ttl=64 time=4.24 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=30 ttl=64 time=4.23 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=31 ttl=64 time=106 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=32 ttl=64 time=5.37 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=33 ttl=64 time=5.40 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=34 ttl=64 time=5.46 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=35 ttl=64 time=4.18 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=36 ttl=64 time=5.41 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=37 ttl=64 time=4.61 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=38 ttl=64 time=4.16 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=39 ttl=64 time=4.37 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=40 ttl=64 time=4.28 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=41 ttl=64 time=21.5 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=42 ttl=64 time=5.51 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=43 ttl=64 time=4.07 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=44 ttl=64 time=4.32 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=45 ttl=64 time=5.53 ms
    64 bytes from dns.zbmc.eu (192.168.1.2): icmp_seq=46 ttl=64 time=3.94 ms
    ^C
    --- dns ping statistics ---
    46 packets transmitted, 44 received, 4.34783% packet loss, time 45126ms
    rtt min/avg/max/mdev = 3.920/12.371/111.937/26.534 ms

This is from a laptop running xubuntu 21.10, the system with hostname dns
is a raspberry pi which is my local DNS server.  Connection by WiFi.

Connecting from another xubuntu 21,10 system which has a hardwired connection
doesn't show any delays so I suspect the problem maybe something to do with
the WiFi - but what?


-- 
Chris Green