diff --git a/tooling/build-stack.sh b/tooling/build-stack.sh
index 9eba664..d5a94be 100755
--- a/tooling/build-stack.sh
+++ b/tooling/build-stack.sh
@@ -116,6 +116,13 @@ up() {
       *.local) ;;
       *) warn "ENABLE_MDNS=true but BASE_DOMAIN=$BASE_DOMAIN is not *.local — mDNS won't resolve it" ;;
     esac
+    pgrep -x avahi-daemon >/dev/null 2>&1 \
+      || warn "host avahi-daemon not detected — the avahi container publishes through it; start it (e.g. 'systemctl start avahi-daemon')"
+    [ -S /run/dbus/system_bus_socket ] \
+      || warn "host D-Bus socket /run/dbus/system_bus_socket missing — avahi publish will fail"
+    local ifc; ifc=$(ip -o link show 2>/dev/null | wc -l)
+    [ "${ifc:-0}" -gt 6 ] \
+      && warn "host has ${ifc} network interfaces — set 'allow-interfaces=<lan-nic>' in /etc/avahi/avahi-daemon.conf, else avahi self-collides (Local name collision)"
   fi
   log "PHASE up (mode=$mode${ENABLE_MDNS:+, mdns=$ENABLE_MDNS})"
   have_script render-config.sh