detect available iperf3 servers in miami , new york and los angeles to have a more precise test of upload and download bandwidth

iperf3-us-cities.sh

#!/usr/bin/env bash

iperf3_us_cities() {
  local url='https://export.iperf3serverlist.net/listed_iperf3_servers.json'
  local sites='los angeles|miami|new york city'

  printf '  last-modified: '
  curl -sI "$url" | grep -i '^last-modified:' | cut -d' ' -f2- | tr -d '\r'
  printf '\n'

  local result
  result=$(curl -s "$url" | jq -r --arg s "$sites" '
    [ .[] | select(.SITE | ascii_downcase | test("^(" + $s + ")$")) ] |
    if length == 0 then
      "WARN: 0 matches for [\($s)] -- schema may have changed",
      "  try: curl -s URL | jq \"[.[].SITE] | unique | sort\""
    else .[] |
      (.["IP/HOST"] // null) as $host |
      if $host == null then
        "# SKIP: no IP/HOST for \(.SITE // "?") (\(.PROVIDER // "?"))"
      else
        (.PORT // "5201") as $fp |
        ($fp | split("-")[0]) as $p |
        (.OPTIONS // "" | split(",") | map(select(length>0)) | join(" ")) as $o |
        "iperf3 -c \($host) -p \($p)" +
        (if ($o | length) > 0 then " \($o)" else "" end) +
        "  # \(.SITE) -- \(.PROVIDER // "?")" +
        (if ($fp | contains("-")) then "  [range: \($fp)]" else "" end)
      end
    end
  ') || { echo "FAIL: curl or jq error -- inspect $url manually"; return 1; }

  if [ -z "$result" ]; then
    echo "FAIL: empty output -- check connectivity or JSON structure"
    return 1
  fi

  echo "$result"
}

iperf3_us_cities

need to improve

iperf3 -c '<domain>' -p '<port>' -t 20 -O 3 --bidir

from https://manpages.debian.org/trixie/iperf3/iperf3.1.en.html

output example

  last-modified: Tue, 03 Mar 2026 20:00:01 GMT

iperf3 -c la.speedtest.clouvider.net -p 5200 -R -6 -u  # Los Angeles -- Clouvider  [range: 5200-5209]
iperf3 -c nyc.speedtest.clouvider.net -p 5201 -R -6 -u  # New York City -- Clouvider  [range: 5201-5209]
iperf3 -c 185.152.67.2 -p 5201 -R -u  # Los Angeles -- DATAPACKET
iperf3 -c 195.181.162.195 -p 5201 -R -u  # Miami -- DATAPACKET
iperf3 -c 23.249.54.234 -p 30000 -R  # Miami -- FortiSASE
iperf3 -c speedtest.lax12.us.leaseweb.net -p 5201 -R -6  # Los Angeles -- LeaseWeb  [range: 5201-5210]
iperf3 -c speedtest.mia11.us.leaseweb.net -p 5201 -R -6  # Miami -- LeaseWeb  [range: 5201-5210]
iperf3 -c speedtest.nyc1.us.leaseweb.net -p 5201 -R -6 -u  # New York City -- LeaseWeb  [range: 5201-5210]

there are other more reliable tools to measure latency like ping , mtr and irtt

a new tool i found recently is

https://radar.cloudflare.com/speedtest

Network Quality Test