diff --git a/bin/upgrade_containers.sh b/bin/upgrade_containers.sh
index 3c62cc2b6..efd3d2c9b 100755
--- a/bin/upgrade_containers.sh
+++ b/bin/upgrade_containers.sh
@@ -163,9 +163,64 @@ cat /home/${USER}/anthias/docker-compose.yml.tmpl \
 # pre-fix behaviour of dropping the bind mount entirely). Fixes
 # the "CEC error" toast on Pi 5 reported in issue #2863.
 case "$DEVICE_TYPE" in
-    pi5)
-        sed -i 's|^\([[:space:]]*\)- "/dev/vchiq:/dev/vchiq"$|\1- "/dev/cec0:/dev/cec0"\n\1- "/dev/cec1:/dev/cec1"|' \
-            /home/${USER}/anthias/docker-compose.yml
+    pi4-64|pi5)
+        CEC_DEV=""
+        if command -v cec-ctl >/dev/null 2>&1; then
+            for DEV in /dev/cec0 /dev/cec1; do
+                [[ -e "$DEV" ]] || continue
+                PHYS_ADDR=$(cec-ctl -d "$DEV" 2>/dev/null \
+                    | grep "Physical Address" | head -1 | awk -F: '{print $2}' | xargs)
+                if [[ -n "$PHYS_ADDR" ]] && [[ "$PHYS_ADDR" != "f.f.f.f" ]]; then
+                    CEC_DEV="$DEV"
+                    break
+                fi
+            done
+        fi
+
+        if [[ -n "$CEC_DEV" ]]; then
+            # libcec only ever probes /dev/cec0 — it doesn't enumerate
+            # /dev/cec1, even when that's the port actually connected
+            # to the TV (confirmed on hardware: with only /dev/cec1
+            # mounted under its real name, cec.init() raises "No
+            # default adapter found"). Remap whichever port is live to
+            # the fixed path /dev/cec0 inside the container, regardless
+            # of which physical micro-HDMI port it corresponds to on
+            # the host.
+            sed -i "s|^\([[:space:]]*\)- \"/dev/vchiq:/dev/vchiq\"\$|\1- \"$CEC_DEV:/dev/cec0\"|" \
+                /home/${USER}/anthias/docker-compose.yml
+        else
+            # cec-ctl isn't on the host, or no port reported a valid
+            # physical address (e.g. the TV was off during the
+            # upgrade). Mount whichever real /dev/cecN nodes actually
+            # exist on the host, under their real names — devices:
+            # fails container start if a listed host path doesn't
+            # exist, so we can't assume both are always present.
+            # If the live port turns out to be /dev/cec1, this will
+            # keep not working until a future upgrade run can detect
+            # it (cec-ctl becomes available, or the TV is on); that's
+            # a known limitation of this degraded fallback.
+            MOUNT_REPL=""
+            if [[ -e /dev/cec0 ]]; then
+                MOUNT_REPL='\1- "/dev/cec0:/dev/cec0"'
+            fi
+            if [[ -e /dev/cec1 ]]; then
+                if [[ -n "$MOUNT_REPL" ]]; then
+                    MOUNT_REPL="${MOUNT_REPL}\\n\\1- \"/dev/cec1:/dev/cec1\""
+                else
+                    MOUNT_REPL='\1- "/dev/cec1:/dev/cec1"'
+                fi
+            fi
+
+            if [[ -n "$MOUNT_REPL" ]]; then
+                sed -i "s|^\([[:space:]]*\)- \"/dev/vchiq:/dev/vchiq\"\$|${MOUNT_REPL}|" \
+                    /home/${USER}/anthias/docker-compose.yml
+            else
+                # Neither node exists — same situation as a board
+                # with no CEC adapter at all; drop the mount entirely.
+                sed -i '/devices:/ {N; /\n.*\/dev\/vchiq:\/dev\/vchiq/d}' \
+                    /home/${USER}/anthias/docker-compose.yml
+            fi
+        fi
         ;;
     x86|arm64)
         if [ -e /dev/cec0 ]; then
diff --git a/src/anthias_server/lib/diagnostics.py b/src/anthias_server/lib/diagnostics.py
index 81bd572ec..32e70a36c 100755
--- a/src/anthias_server/lib/diagnostics.py
+++ b/src/anthias_server/lib/diagnostics.py
@@ -175,7 +175,11 @@ def cec_available() -> bool:
     means the adapter *could* work, not that it will: the actual
     success/failure is surfaced by ``set_display_power``'s toast.
     """
-    return os.path.exists('/dev/cec0') or os.path.exists('/dev/vchiq')
+    return (
+        os.path.exists('/dev/cec0')
+        or os.path.exists('/dev/cec1')
+        or os.path.exists('/dev/vchiq')
+    )
 
 
 def get_uptime() -> float:
diff --git a/tests/test_app.py b/tests/test_app.py
index 9f291af53..09dcd98d1 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -1865,11 +1865,13 @@ def test_skip_buttons_publish_correct_command(
 # 8. Display power (experimental, HDMI-CEC) — issue #2575
 # ---------------------------------------------------------------------------
 #
-# The section is gated on cec_available(), which stats /dev/cec0 and
-# /dev/vchiq. Neither exists in the test container by default, so the
-# section is hidden on every other settings test. To exercise the
-# visible state we stub /dev/vchiq with a plain file before navigating
-# and remove it on teardown.
+# The section is gated on cec_available(), which stats /dev/cec0,
+# /dev/cec1, and /dev/vchiq. The /dev/cec1 check covers Pi 4/5 hosts
+# where the display is wired to the second micro-HDMI port (issue
+# #2863). None of these exist in the test container by default, so
+# the section is hidden on every other settings test. To exercise the
+# visible state we stub one of them with a plain file before
+# navigating and remove it on teardown.
 
 # Screenshot capture is OFF by default. The original PR (#2886) used
 # screenshots for a one-time UX review; running them on every CI cycle
@@ -1921,6 +1923,32 @@ def cec_stub_device() -> Any:
                 pass
 
 
+@pytest.fixture
+def cec1_stub_device() -> Any:
+    """Create a stub `/dev/cec1` so `diagnostics.cec_available()`
+    returns True via the second-HDMI-port path rather than
+    `/dev/vchiq`. Exercises the Pi 4/5 dual-micro-HDMI case where the
+    display is wired to the second port and only `/dev/cec1` exists
+    (issue #2863's actual failure mode).
+    """
+    path = '/dev/cec1'
+    created = False
+    if not os.path.exists(path):
+        try:
+            open(path, 'w').close()
+            created = True
+        except OSError:
+            pytest.skip('cannot stub /dev/cec1 in this environment')
+    try:
+        yield path
+    finally:
+        if created:
+            try:
+                os.remove(path)
+            except FileNotFoundError:
+                pass
+
+
 @pytest.mark.integration
 @pytest.mark.django_db(transaction=True)
 def test_display_power_section_hidden_without_cec_adapter(
@@ -1929,7 +1957,11 @@ def test_display_power_section_hidden_without_cec_adapter(
     """No /dev/cec0 or /dev/vchiq in the container by default — the
     experimental section must NOT render. Guards against accidentally
     surfacing CEC controls on x86 / non-CEC hardware."""
-    if os.path.exists('/dev/vchiq') or os.path.exists('/dev/cec0'):
+    if (
+        os.path.exists('/dev/vchiq')
+        or os.path.exists('/dev/cec0')
+        or os.path.exists('/dev/cec1')
+    ):
         pytest.skip('CEC device present; cannot test the hidden case')
     page.goto(SETTINGS_URL)
     expect(
@@ -1975,6 +2007,20 @@ def test_display_power_section_visible_with_cec_adapter(
         )
 
 
+@pytest.mark.integration
+@pytest.mark.django_db(transaction=True)
+def test_display_power_section_visible_with_cec1_only(
+    reset_assets: None, page: Page, cec1_stub_device: str
+) -> None:
+    """Pi 4/5 with the display on the second micro-HDMI port exposes
+    only /dev/cec1, not /dev/cec0 — the section must still render
+    instead of silently disappearing (issue #2863)."""
+    page.goto(SETTINGS_URL)
+    expect(page.get_by_role('heading', name='Display power')).to_be_visible()
+    expect(page.get_by_role('button', name='Turn display on')).to_be_visible()
+    expect(page.get_by_role('button', name='Turn display off')).to_be_visible()
+
+
 @pytest.mark.integration
 @pytest.mark.django_db(transaction=True)
 def test_display_power_button_click_surfaces_error_toast(
diff --git a/tests/test_diagnostics.py b/tests/test_diagnostics.py
index 1335c37e0..34a95a004 100644
--- a/tests/test_diagnostics.py
+++ b/tests/test_diagnostics.py
@@ -289,6 +289,17 @@ def test_cec_available_true_when_cec0_present() -> None:
         assert diagnostics.cec_available() is True
 
 
+def test_cec_available_true_when_only_cec1_present() -> None:
+    """Pi 4/5 displays wired to the second micro-HDMI port only
+    expose /dev/cec1 — the gate must not assume /dev/cec0 is the only
+    possible CEC node (the actual failure mode behind the
+    device-routing fix for issue #2863)."""
+    with mock.patch.object(
+        os.path, 'exists', side_effect=lambda p: p == '/dev/cec1'
+    ):
+        assert diagnostics.cec_available() is True
+
+
 def test_cec_available_true_when_vchiq_present() -> None:
     with mock.patch.object(
         os.path, 'exists', side_effect=lambda p: p == '/dev/vchiq'