diff --git a/INSTALL.md b/INSTALL.md
index 222eef6..db4630b 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -144,6 +144,34 @@ sudo systemd-tmpfiles --create /etc/tmpfiles.d/svxportal-tglist.conf
 This creates `/etc/svxlink/tglist.json` owned by `www-data`. The path is
 `tglist_file` in `config.php`; change both if you want it elsewhere.
 
+### 6b. Optional: follower box that mirrors another portal's talkgroup list
+
+If you run several reflectors and want ONE talkgroup list, one portal is the
+master (its list is edited in the web) and the others pull it four times a day
+with a systemd timer. Nothing but `curl` and `python3` is involved.
+
+```bash
+sudo cp install/systemd/svxportal-tglist-sync.service install/systemd/svxportal-tglist-sync.timer /etc/systemd/system/
+sudo cp install/systemd/tglist-sync.sh /etc/svxlink/tglist-sync.sh && sudo chmod 755 /etc/svxlink/tglist-sync.sh
+sudo cp install/systemd/default-svxportal-tglist-sync /etc/default/svxportal-tglist-sync
+sudoedit /etc/default/svxportal-tglist-sync      # UPSTREAM = the master's https://.../tglist.php
+sudo systemctl daemon-reload
+sudo systemctl enable --now svxportal-tglist-sync.timer
+sudo systemctl start svxportal-tglist-sync.service && journalctl -u svxportal-tglist-sync -n 3
+```
+
+On the master, or on a standalone box, do **not** install this (or leave
+`UPSTREAM` empty; the script then exits without touching the file).
+
+Other systemd notes:
+
+- `svxreflector.service` is used **unmodified** from the SvxLink package. No
+  drop-in is needed for the portal.
+- Redis runs from Debian's `redis-server@.service` template (step 3); no unit
+  file to add.
+- There are no cron jobs. PHP session cleanup is Debian's stock
+  `phpsessionclean.timer`.
+
 ## 7. nginx + TLS
 
 ```bash
diff --git a/install/systemd/default-svxportal-tglist-sync b/install/systemd/default-svxportal-tglist-sync
new file mode 100644
index 0000000..95b70bb
--- /dev/null
+++ b/install/systemd/default-svxportal-tglist-sync
@@ -0,0 +1,8 @@
+# Follower-box TG list sync (svxportal-tglist-sync.service/.timer).
+#
+# UPSTREAM = the master's public TG list URL. When set, this box is a FOLLOWER:
+# the timer pulls that list into DEST 4x/day and the web TG editor is hidden.
+# Leave UPSTREAM empty on the MASTER and on fully-standalone boxes — they own the
+# list locally and edit it in the web; the sync is then a no-op.
+UPSTREAM=https://svxportal.my.domain.com/tglist.php
+DEST=/etc/svxlink/tglist.json
diff --git a/install/systemd/svxportal-tglist-sync.service b/install/systemd/svxportal-tglist-sync.service
new file mode 100644
index 0000000..6271ba7
--- /dev/null
+++ b/install/systemd/svxportal-tglist-sync.service
@@ -0,0 +1,10 @@
+[Unit]
+Description=Sync canonical TG list from svxportal master
+Documentation=file:/etc/svxlink/tglist-sync.sh
+Wants=network-online.target
+After=network-online.target
+
+[Service]
+Type=oneshot
+EnvironmentFile=/etc/default/svxportal-tglist-sync
+ExecStart=/bin/bash /etc/svxlink/tglist-sync.sh
diff --git a/install/systemd/svxportal-tglist-sync.timer b/install/systemd/svxportal-tglist-sync.timer
new file mode 100644
index 0000000..1ec27c5
--- /dev/null
+++ b/install/systemd/svxportal-tglist-sync.timer
@@ -0,0 +1,12 @@
+[Unit]
+Description=Sync canonical TG list from svxportal master (4x/day)
+
+[Timer]
+# Shortly after boot, then every 6 hours (00,06,12,18). Persistent catches a
+# missed run if the box was off at the scheduled time.
+OnBootSec=2min
+OnCalendar=*-*-* 00,06,12,18:00:00
+Persistent=true
+
+[Install]
+WantedBy=timers.target
diff --git a/install/systemd/tglist-sync.sh b/install/systemd/tglist-sync.sh
new file mode 100644
index 0000000..b85217d
--- /dev/null
+++ b/install/systemd/tglist-sync.sh
@@ -0,0 +1,38 @@
+#!/bin/bash
+# Follower-box sync of the canonical TG list.
+#
+# Pulls the master list from the svxportal master (its public /tglist.php) into
+# the LOCAL /etc/svxlink/tglist.json, so every local program reads ONE identical
+# list: svxdr (Lastheard TG name/Location) and the box's own /tglist.php (TG
+# Monitor) both read that local file. No extra daemon — a plain curl run by a
+# systemd timer.
+#
+# Master and fully-standalone boxes OWN the file locally (web editor) and must
+# NOT run this — leave UPSTREAM empty there (the timer is a no-op / not enabled).
+set -euo pipefail
+: "${UPSTREAM:=}"
+: "${DEST:=/etc/svxlink/tglist.json}"
+
+# Empty UPSTREAM = this box owns its list; nothing to sync.
+[ -n "$UPSTREAM" ] || { echo "UPSTREAM empty — this box owns its TG list, skipping sync"; exit 0; }
+
+tmp="$(mktemp)"; out="$(mktemp)"
+trap 'rm -f "$tmp" "$out"' EXIT
+
+curl -fsS -m 20 "$UPSTREAM" -o "$tmp"
+
+# Keep ONLY the canonical shape {tgs:[...],requests:[]}. Refuse to overwrite the
+# live file with anything that is not a valid list (a 404/HTML/partial body must
+# never blank the TG names) — last good copy then simply stays.
+python3 - "$tmp" "$out" <<'PY'
+import json, sys
+d = json.load(open(sys.argv[1]))
+tgs = d.get("tgs")
+if not isinstance(tgs, list) or not tgs:
+    raise SystemExit("upstream has no tgs list — refusing to overwrite")
+json.dump({"tgs": tgs, "requests": []}, open(sys.argv[2], "w"), indent=2)
+PY
+
+# www-data owns it so the web can still read it; atomic replace via install.
+install -o www-data -g www-data -m 0664 "$out" "$DEST"
+echo "TG list synced from $UPSTREAM -> $DEST"