diff --git a/start.sh b/start.sh
index 660a7e4..edac763 100755
--- a/start.sh
+++ b/start.sh
@@ -121,67 +121,6 @@ normalize_host() {
   esac
 }
 
-common_domain_suffix_two() {
-  local host_a="$1"
-  local host_b="$2"
-  local IFS='.'
-  local -a parts_a=()
-  local -a parts_b=()
-  read -ra parts_a <<< "$host_a"
-  read -ra parts_b <<< "$host_b"
-  local i=$(( ${#parts_a[@]} - 1 ))
-  local j=$(( ${#parts_b[@]} - 1 ))
-  local suffix=""
-
-  while [ $i -ge 0 ] && [ $j -ge 0 ]; do
-    if [ "${parts_a[$i]}" = "${parts_b[$j]}" ]; then
-      if [ -z "$suffix" ]; then
-        suffix="${parts_a[$i]}"
-      else
-        suffix="${parts_a[$i]}.$suffix"
-      fi
-      ((i--))
-      ((j--))
-    else
-      break
-    fi
-  done
-
-  printf '%s\n' "$suffix"
-}
-
-common_domain_suffix() {
-  if [ "$#" -eq 0 ]; then
-    return
-  fi
-
-  local suffix="$1"
-  shift
-
-  while [ "$#" -gt 0 ] && [ -n "$suffix" ]; do
-    suffix="$(common_domain_suffix_two "$suffix" "$1")"
-    shift
-  done
-
-  printf '%s\n' "$suffix"
-}
-
-derive_default_rp_id() {
-  local hosts=("$PHOTOS_HOST")
-  if [ "$USE_SUBDOMAIN_ROUTING" = true ]; then
-    hosts+=("$ACCOUNTS_HOST" "$AUTH_HOST" "$CAST_HOST" "$ALBUMS_HOST" "$FAMILY_HOST")
-  fi
-
-  local suffix
-  suffix="$(common_domain_suffix "${hosts[@]}")"
-
-  if [ -n "$suffix" ]; then
-    printf '%s\n' "$suffix"
-  else
-    printf '%s\n' "$PHOTOS_HOST"
-  fi
-}
-
 ACCOUNTS_HOST="$(normalize_host "$ACCOUNTS_HOST")"
 AUTH_HOST="$(normalize_host "$AUTH_HOST")"
 CAST_HOST="$(normalize_host "$CAST_HOST")"
@@ -216,11 +155,7 @@ else
   API_BASE="$BASE_URL"
 fi
 API_ORIGIN="${API_BASE}/api"
-if [ -n "${WEBAUTHN_RP_ID:-}" ]; then
-  RP_ID="$WEBAUTHN_RP_ID"
-else
-  RP_ID="$(derive_default_rp_id)"
-fi
+RP_ID="$PHOTOS_HOST"
 
 log INFO "Application base URL: $BASE_URL"
 log INFO "Relying party ID: $RP_ID"
@@ -1054,8 +989,7 @@ cat > "$CADDY_CONFIG" <<EOF_CADDY
         respond 204
     }
 
-    @api_host host ${PHOTOS_HOST}
-    handle_path @api_host /api/* {
+    handle_path /api/* {
         @api_cors_subdomain header Origin *
         header @api_cors_subdomain {
             Access-Control-Allow-Origin {http.request.header.Origin}
@@ -1108,7 +1042,6 @@ cat > "$CADDY_CONFIG" <<EOF_CADDY
     }
 
     @museum_api_get {
-        host ${PHOTOS_HOST}
         method GET HEAD
         path_regexp museum_api_get ^/(admin|authenticator|billing|cast|collections|custom-domain|diff|discount|email-hash|emails-from-hashes|emergency-contacts|family|file|file-link|files|fire|info|job|mail|metrics|multipart-upload-urls|offers|options|pass-info|passkeys|public-collection|push|queue|remote-store|storage-bonus|thumbnail|trash|unknown-api|upload-urls|user|user-entity|verify-password)(/|$)
     }
@@ -1122,7 +1055,6 @@ cat > "$CADDY_CONFIG" <<EOF_CADDY
     }
 
     @write_methods {
-        host ${PHOTOS_HOST}
         not method GET
         not method HEAD
     }
@@ -1218,11 +1150,7 @@ cat > "$CADDY_CONFIG" <<EOF_CADDY
         respond 204
     }
 
-    @api_photos {
-        host ${PHOTOS_HOST}
-        path /api/*
-    }
-    handle @api_photos {
+    handle_path /api/* {
         @api_cors_path header Origin *
         header @api_cors_path {
             Access-Control-Allow-Origin {http.request.header.Origin}
@@ -1239,7 +1167,6 @@ cat > "$CADDY_CONFIG" <<EOF_CADDY
             header_up X-Forwarded-For {http.request.header.X-Forwarded-For}
             header_up X-Forwarded-Proto {http.request.header.X-Forwarded-Proto}
         }
-        }
     }
 
     handle /health {
@@ -1276,7 +1203,6 @@ cat > "$CADDY_CONFIG" <<EOF_CADDY
     }
 
     @museum_api_get_path {
-        host ${PHOTOS_HOST}
         method GET HEAD
         path_regexp museum_api_get_path ^/(admin|authenticator|billing|cast|collections|custom-domain|diff|discount|email-hash|emails-from-hashes|emergency-contacts|family|file|file-link|files|fire|info|job|mail|metrics|multipart-upload-urls|offers|options|pass-info|passkeys|public-collection|push|queue|remote-store|storage-bonus|thumbnail|trash|unknown-api|upload-urls|user|user-entity|verify-password)(/|$)
     }
@@ -1290,7 +1216,6 @@ cat > "$CADDY_CONFIG" <<EOF_CADDY
     }
 
     @write_methods_path {
-        host ${PHOTOS_HOST}
         not method GET
         not method HEAD
     }