diff --git a/setup-environment.sh b/setup-environment.sh
index c932003bd..bd62017b9 100755
--- a/setup-environment.sh
+++ b/setup-environment.sh
@@ -421,13 +421,21 @@ tailnet_node_name() {
 }
 
 # Peers on this tailnet whose name looks like a hummingbot-api node, newline
-# separated. Matches the requested name and the -1/-2 suffixes Tailscale adds,
-# so the machine we are looking for is found under whichever one it got.
+# separated.
+#
+# The suffix is deliberately `-.+` and not `-[0-9]+`. Tailscale's own
+# de-duplication only ever appends numbers, but TAILSCALE_HOSTNAME is a
+# setting, and a deployment that names its API per desk -- hummingbot-api-cornell,
+# hummingbot-api-eu -- is the normal way to run more than one. Matching only
+# numbers found nothing for those, and "nothing" is the branch that warns
+# "deploy it on that machine first" about a node sitting right there in
+# `tailscale status`, then asks the operator to type the name it just declined
+# to recognise.
 tailnet_api_peers() {
     local want="${1:-hummingbot-api}"
     tailscale status --peers 2>/dev/null \
         | awk '{print $2}' \
-        | grep -E "^${want}(-[0-9]+)?$" || true
+        | grep -E "^${want}(-.+)?$" || true
 }
 
 # Make sure a tailscaled is running, then `tailscale up`.
@@ -1164,16 +1172,42 @@ if [ -z "${DEPLOY_HUMMINGBOT_API:-}" ] || [ "$finish_remote_api" = true ]; then
             ts_hostname=""
             _ts_candidates="$(tailnet_api_peers hummingbot-api)"
             _ts_count="$(printf '%s' "$_ts_candidates" | grep -c . || true)"
-            if [ "${_ts_count:-0}" -eq 1 ]; then
+            if [ "${_ts_count:-0}" -eq 1 ] && [ "$_ts_candidates" = "hummingbot-api" ]; then
+                # The unsuffixed name, and the only match. Nothing to choose
+                # between, and it is the name hummingbot-api's own setup asks
+                # for, so this is the node in every ordinary install.
                 ts_hostname="$_ts_candidates"
                 msg_ok "Found it on your tailnet: $ts_hostname"
+            elif [ "${_ts_count:-0}" -eq 1 ]; then
+                # One match, but under a suffix -- hummingbot-api-1, or a name
+                # somebody chose. Being alone is not evidence it is the right
+                # one: a stale node, a colleague's staging box, or another
+                # desk's API is just as alone, and accepting it silently writes
+                # it into config.yml where the next sign of trouble is a 401
+                # against a machine the operator never meant to reach. Shown
+                # and confirmed instead, with Enter as the answer when it is
+                # right, which is the common case.
+                msg_ok "Found one hummingbot-api node on your tailnet: $_ts_candidates"
+                msg_info "That is not the default name, so it is worth a look before it"
+                msg_info "goes in config.yml. Press Enter to use it, or type another."
+                prompt_visible "hummingbot-api host" "$_ts_candidates" "ts_hostname"
+                ts_hostname="${ts_hostname:-$_ts_candidates}"
             elif [ "${_ts_count:-0}" -gt 1 ]; then
                 msg_warn "More than one hummingbot-api node on this tailnet:"
                 printf '%s\n' "$_ts_candidates" | while IFS= read -r _c; do
                     [ -n "$_c" ] && echo "      • $_c"
                 done
-                msg_info "Tailscale adds -1, -2 ... when a name is taken, so these are"
-                msg_info "different machines. Pick the one you just deployed."
+                # Deliberately does NOT say "Tailscale adds -1, -2 when a name
+                # is taken, so pick the one you just deployed". Running several
+                # APIs on purpose -- hummingbot-api-1, hummingbot-api-2 -- is a
+                # normal deployment, and there those suffixes are chosen names,
+                # not collision artifacts. The old wording told such an operator
+                # their own naming was an accident, and "the one you just
+                # deployed" is the wrong instruction anyway when Condor is being
+                # pointed at an instance that has been up for weeks.
+                msg_info "These are separate machines -- deployments named on purpose, or"
+                msg_info "names Tailscale suffixed because one was already taken."
+                msg_info "Pick the one this Condor should talk to."
                 prompt_required_visible "Which node is your hummingbot-api?" "ts_hostname" "Name cannot be empty"
             else
                 msg_warn "No hummingbot-api node is visible on this tailnet yet."
diff --git a/tests/test_setup_tailnet_peers.py b/tests/test_setup_tailnet_peers.py
new file mode 100644
index 000000000..d399369ed
--- /dev/null
+++ b/tests/test_setup_tailnet_peers.py
@@ -0,0 +1,144 @@
+"""`tailnet_api_peers` in setup-environment.sh, exercised as shell.
+
+The helper decides which tailnet node the wizard writes into config.yml as
+the hummingbot-api host, and getting it wrong is not a visible failure: the
+wrong node is very likely running the same software, so it answers, and the
+mistake surfaces as "401 Incorrect username or password" against a password
+that was never wrong.
+
+There is no bats in this repo and no reason to add one for a single awk/grep
+pipeline, so the function is sourced out of the script with a `tailscale`
+stub ahead of it on PATH. That runs the real line, not a Python
+reimplementation of it -- a copy of the regex in a test asserts only that the
+copy matches itself.
+"""
+
+from __future__ import annotations
+
+import subprocess
+from pathlib import Path
+
+import pytest
+
+SETUP = Path(__file__).resolve().parent.parent / "setup-environment.sh"
+
+
+def run_peers(
+    tmp_path: Path, status_output: str, want: str = "hummingbot-api"
+) -> list[str]:
+    """Return `tailnet_api_peers <want>` over a stubbed `tailscale status`."""
+    stub_dir = tmp_path / "bin"
+    stub_dir.mkdir(exist_ok=True)
+    stub = stub_dir / "tailscale"
+    peers = tmp_path / "peers.txt"
+    peers.write_text(status_output)
+    stub.write_text(f'#!/bin/sh\ncat "{peers}"\n')
+    stub.chmod(0o755)
+
+    # Pull just the function out: sourcing the whole script would run an
+    # installer. Everything from its definition to the closing brace.
+    src = SETUP.read_text()
+    start = src.index("tailnet_api_peers() {")
+    end = src.index("\n}\n", start) + len("\n}\n")
+    func = src[start:end]
+
+    proc = subprocess.run(
+        ["bash", "-c", f'PATH="{stub_dir}:$PATH"\n{func}\ntailnet_api_peers "{want}"'],
+        capture_output=True,
+        text=True,
+        timeout=30,
+    )
+    assert proc.returncode == 0, proc.stderr
+    return [ln for ln in proc.stdout.splitlines() if ln.strip()]
+
+
+def status(*names: str) -> str:
+    return "".join(
+        f"100.64.0.{i + 1}\t{n}\tdavid@\tlinux\t-\n" for i, n in enumerate(names)
+    )
+
+
+# ── the suffixes Tailscale itself assigns ──────────────────────────────
+
+
+def test_finds_the_unsuffixed_name(tmp_path):
+    assert run_peers(tmp_path, status("hummingbot-api")) == ["hummingbot-api"]
+
+
+def test_finds_numeric_collision_suffixes(tmp_path):
+    out = run_peers(tmp_path, status("hummingbot-api-1", "hummingbot-api-2"))
+    assert out == ["hummingbot-api-1", "hummingbot-api-2"]
+
+
+# ── the suffixes an operator assigns, which is what this PR is about ───
+
+
+@pytest.mark.parametrize("name", ["hummingbot-api-cornell", "hummingbot-api-eu"])
+def test_finds_desk_named_nodes(tmp_path, name):
+    """The regression: TAILSCALE_HOSTNAME is a setting, not only a collision."""
+    assert run_peers(tmp_path, status(name)) == [name]
+
+
+def test_deliberate_numeric_fleet_all_found(tmp_path):
+    """A planned multi-instance deployment, the case that motivated the reword."""
+    out = run_peers(
+        tmp_path, status("hummingbot-api", "hummingbot-api-1", "hummingbot-api-2")
+    )
+    assert out == ["hummingbot-api", "hummingbot-api-1", "hummingbot-api-2"]
+    assert len(out) > 1, "must reach the pick-one branch, never auto-select"
+
+
+# ── names that must NOT be claimed ─────────────────────────────────────
+
+
+@pytest.mark.parametrize(
+    "name",
+    [
+        "condor",
+        "condor-hackathon",
+        "condor-hackathon-server",
+        "condor1",
+        "hbapi",
+        "my-hummingbot-api",  # suffix match, not prefix -- anchored ^
+    ],
+)
+def test_ignores_unrelated_nodes(tmp_path, name):
+    assert run_peers(tmp_path, status(name)) == []
+
+
+def test_ignores_the_prefix_without_a_separator(tmp_path):
+    """`hummingbot-apis` is a different word, not a suffixed hummingbot-api."""
+    assert run_peers(tmp_path, status("hummingbot-apis")) == []
+
+
+def test_picks_only_the_api_out_of_a_mixed_tailnet(tmp_path):
+    out = run_peers(
+        tmp_path,
+        status(
+            "condor-hackathon",
+            "hummingbot-api-cornell",
+            "condor1",
+            "someones-laptop",
+        ),
+    )
+    assert out == ["hummingbot-api-cornell"]
+
+
+# ── shape of the output ────────────────────────────────────────────────
+
+
+def test_empty_tailnet_is_empty_not_an_error(tmp_path):
+    """The no-match branch must be reachable: `|| true` keeps grep's 1 quiet."""
+    assert run_peers(tmp_path, "") == []
+
+
+def test_reads_the_name_column_not_the_address(tmp_path):
+    out = run_peers(tmp_path, status("hummingbot-api"))
+    assert out == ["hummingbot-api"]
+    assert not any(c.startswith("100.") for c in out)
+
+
+def test_custom_want_is_honoured(tmp_path):
+    """The parameter is real, even though today's only caller hardcodes it."""
+    out = run_peers(tmp_path, status("condor", "condor-hackathon"), want="condor")
+    assert out == ["condor", "condor-hackathon"]