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

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