diff --git a/internal/web/service/outbound/outbound.go b/internal/web/service/outbound/outbound.go
index 8b28eedfb..1e9ce2ad2 100644
--- a/internal/web/service/outbound/outbound.go
+++ b/internal/web/service/outbound/outbound.go
@@ -157,7 +157,7 @@ func (s *OutboundService) testOutboundTCP(outboundJSON string) (*TestOutboundRes
 	}
 	tag, _ := ob["tag"].(string)
 	protocol, _ := ob["protocol"].(string)
-	if protocol == "blackhole" || protocol == "freedom" || tag == "blocked" {
+	if equalsAnyFold(protocol, "blackhole", "freedom") || tag == "blocked" {
 		return &TestOutboundResult{Tag: tag, Mode: "tcp", Success: false, Error: "Outbound has no testable endpoint"}, nil
 	}
 
diff --git a/internal/web/service/outbound/probe_protocol_case_test.go b/internal/web/service/outbound/probe_protocol_case_test.go
index 4079d515f..8109df16f 100644
--- a/internal/web/service/outbound/probe_protocol_case_test.go
+++ b/internal/web/service/outbound/probe_protocol_case_test.go
@@ -110,6 +110,37 @@ func TestBuildBatchTestConfigReadsTheProtocolIDLikeTheCore(t *testing.T) {
 	}
 }
 
+func TestTestOutboundsRejectsUntestableIDsInAnyCase(t *testing.T) {
+	tests := []struct {
+		name     string
+		protocol string
+	}{
+		{"canonical freedom", "freedom"},
+		{"capitalised freedom", "Freedom"},
+		{"upper freedom", "FREEDOM"},
+		{"canonical blackhole", "blackhole"},
+		{"capitalised blackhole", "Blackhole"},
+	}
+
+	const wantErr = "Outbound has no testable endpoint"
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			batch := mustJSON(t, []any{map[string]any{"tag": "t1", "protocol": tt.protocol}})
+			results, err := (&OutboundService{}).TestOutbounds(batch, "", "", "tcp")
+			if err != nil {
+				t.Fatalf("TestOutbounds: %v", err)
+			}
+			r := results[0]
+			if r.Success {
+				t.Errorf("%q outbound = %+v, want a rejection", tt.protocol, r)
+			}
+			if r.Error != wantErr {
+				t.Errorf("%q error = %q, want %q", tt.protocol, r.Error, wantErr)
+			}
+		})
+	}
+}
+
 func TestTestOutboundsTCPLaneReadsProtocolIDCaseInsensitively(t *testing.T) {
 	l, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {
diff --git a/internal/web/service/xray_setting_routing_sync.go b/internal/web/service/xray_setting_routing_sync.go
index c230b6f49..29961d770 100644
--- a/internal/web/service/xray_setting_routing_sync.go
+++ b/internal/web/service/xray_setting_routing_sync.go
@@ -2,6 +2,7 @@ package service
 
 import (
 	"encoding/json"
+	"strings"
 )
 
 var routingMatcherKeys = []string{
@@ -142,7 +143,7 @@ func replaceInboundTagInOutbounds(outbounds []any, oldTag, newTag string) bool {
 			continue
 		}
 		proto, _ := out["protocol"].(string)
-		if proto != "loopback" {
+		if !strings.EqualFold(proto, "loopback") {
 			continue
 		}
 		settings, ok := out["settings"].(map[string]any)
@@ -167,7 +168,7 @@ func removeInboundTagFromOutbounds(outbounds []any, deletedTag string) bool {
 			continue
 		}
 		proto, _ := out["protocol"].(string)
-		if proto != "loopback" {
+		if !strings.EqualFold(proto, "loopback") {
 			continue
 		}
 		settings, ok := out["settings"].(map[string]any)
diff --git a/internal/web/service/xray_setting_routing_sync_test.go b/internal/web/service/xray_setting_routing_sync_test.go
index cf3e1b7ec..effe8c7eb 100644
--- a/internal/web/service/xray_setting_routing_sync_test.go
+++ b/internal/web/service/xray_setting_routing_sync_test.go
@@ -221,6 +221,73 @@ func TestRemoveInboundTagReferences_RemovesOneTagFromMultiInboundRule(t *testing
 	}
 }
 
+// The core lowercases a protocol id before resolving the handler, so "Loopback"
+// is the loopback outbound whose inboundTag has to follow the inbound it names.
+func TestReplaceInboundTagInOutbounds_ReadsTheProtocolIDLikeTheCore(t *testing.T) {
+	tests := []struct {
+		name     string
+		protocol any
+		want     bool
+		wantTag  any
+	}{
+		{"canonical loopback is rewritten", "loopback", true, "new-tag"},
+		{"capitalised loopback is rewritten", "Loopback", true, "new-tag"},
+		{"uppercase loopback is rewritten", "LOOPBACK", true, "new-tag"},
+		{"another protocol keeps its tag", "vmess", false, "old-tag"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			outbounds := []any{map[string]any{
+				"protocol": tt.protocol,
+				"settings": map[string]any{"inboundTag": "old-tag"},
+			}}
+			if got := replaceInboundTagInOutbounds(outbounds, "old-tag", "new-tag"); got != tt.want {
+				t.Errorf("changed = %v, want %v", got, tt.want)
+			}
+			settings := outbounds[0].(map[string]any)["settings"].(map[string]any)
+			if got := settings["inboundTag"]; got != tt.wantTag {
+				t.Errorf("inboundTag = %v, want %v", got, tt.wantTag)
+			}
+		})
+	}
+}
+
+func TestRemoveInboundTagFromOutbounds_ReadsTheProtocolIDLikeTheCore(t *testing.T) {
+	tests := []struct {
+		name     string
+		protocol any
+		want     bool
+		wantTag  any
+	}{
+		{"canonical loopback is cleared", "loopback", true, nil},
+		{"capitalised loopback is cleared", "Loopback", true, nil},
+		{"uppercase loopback is cleared", "LOOPBACK", true, nil},
+		{"another protocol keeps its tag", "vmess", false, "gone-tag"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			outbounds := []any{map[string]any{
+				"protocol": tt.protocol,
+				"settings": map[string]any{"inboundTag": "gone-tag"},
+			}}
+			if got := removeInboundTagFromOutbounds(outbounds, "gone-tag"); got != tt.want {
+				t.Errorf("changed = %v, want %v", got, tt.want)
+			}
+			settings := outbounds[0].(map[string]any)["settings"].(map[string]any)
+			got, ok := settings["inboundTag"]
+			if tt.wantTag == nil {
+				if ok {
+					t.Errorf("inboundTag = %v, want the key gone", got)
+				}
+				return
+			}
+			if !ok || got != tt.wantTag {
+				t.Errorf("inboundTag = %v (present=%v), want %v", got, ok, tt.wantTag)
+			}
+		})
+	}
+}
+
 func findRuleByOutbound(t *testing.T, template, outbound string) map[string]any {
 	t.Helper()
 	for _, rule := range routingRulesFromTemplate(t, template) {