diff --git a/weed/s3api/auth_signature_v4.go b/weed/s3api/auth_signature_v4.go
index 05805f2ad..963cf12a0 100644
--- a/weed/s3api/auth_signature_v4.go
+++ b/weed/s3api/auth_signature_v4.go
@@ -769,7 +769,7 @@ func extractSignedHeaders(signedHeaders []string, r *http.Request) (http.Header,
 	extractedSignedHeaders := make(http.Header)
 	for _, header := range signedHeaders {
 		// `host` is not a case-sensitive header, unlike other headers such as `x-amz-date`.
-		if header == "host" {
+		if strings.ToLower(header) == "host" {
 			// Get host value.
 			hostHeaderValue := extractHostHeader(r)
 			extractedSignedHeaders[header] = []string{hostHeaderValue}
@@ -815,12 +815,12 @@ func extractHostHeader(r *http.Request) string {
 		} else {
 			host = strings.TrimSpace(forwardedHost)
 		}
-		port = forwardedPort
 		if h, p, err := net.SplitHostPort(host); err == nil {
 			host = h
-			if port == "" {
-				port = p
-			}
+			port = p
+		}
+		if forwardedPort != "" && isDefaultPort(scheme, port) {
+			port = forwardedPort
 		}
 	} else {
 		host = r.Host
diff --git a/weed/s3api/auth_signature_v4_test.go b/weed/s3api/auth_signature_v4_test.go
index 849d895b5..782ce6a5b 100644
--- a/weed/s3api/auth_signature_v4_test.go
+++ b/weed/s3api/auth_signature_v4_test.go
@@ -292,6 +292,47 @@ func TestExtractHostHeader(t *testing.T) {
 			forwardedProto: "http",
 			expected:       "[::ffff:127.0.0.1]:8080",
 		},
+		{
+			name:       "Simple port 442",
+			hostHeader: "bucket.domain.com:442",
+			expected:   "bucket.domain.com:442",
+		},
+		{
+			name:          "Port 442 with X-Forwarded-Host",
+			hostHeader:    "backend:8333",
+			forwardedHost: "bucket.domain.com:442",
+			expected:      "bucket.domain.com:442",
+		},
+		{
+			name:          "Port 442 with X-Forwarded-Port",
+			hostHeader:    "backend:8333",
+			forwardedHost: "bucket.domain.com",
+			forwardedPort: "442",
+			expected:      "bucket.domain.com:442",
+		},
+		{
+			name:           "HTTPS with port 442 (should NOT strip)",
+			hostHeader:     "bucket.domain.com:442",
+			forwardedProto: "https",
+			expected:       "bucket.domain.com:442",
+		},
+		{
+			name:          "X-Forwarded-Host with multiple hosts (including port)",
+			forwardedHost: "bucket.domain.com:442, internal.proxy",
+			expected:      "bucket.domain.com:442",
+		},
+		{
+			name:       "IPv6 with port",
+			hostHeader: "[2001:db8::1]:442",
+			expected:   "[2001:db8::1]:442",
+		},
+		{
+			name:           "X-Forwarded-Host with port 442, but X-Forwarded-Port is 80 (should PREFER 442)",
+			forwardedHost:  "bucket.domain.com:442",
+			forwardedPort:  "80",
+			forwardedProto: "http",
+			expected:       "bucket.domain.com:442",
+		},
 	}
 
 	for _, tt := range tests {
@@ -322,3 +363,40 @@ func TestExtractHostHeader(t *testing.T) {
 		})
 	}
 }
+
+func TestExtractSignedHeadersCase(t *testing.T) {
+	tests := []struct {
+		name        string
+		host        string
+		signedHeads []string
+		expected    string
+	}{
+		{
+			name:        "lowercase host",
+			host:        "bucket.domain.com:442",
+			signedHeads: []string{"host"},
+			expected:    "host:bucket.domain.com:442\n",
+		},
+		{
+			name:        "uppercase Host",
+			host:        "bucket.domain.com:442",
+			signedHeads: []string{"Host"},
+			expected:    "host:bucket.domain.com:442\n",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r, _ := http.NewRequest("GET", "http://"+tt.host+"/", nil)
+			r.Host = tt.host
+			extracted, errCode := extractSignedHeaders(tt.signedHeads, r)
+			if errCode != s3err.ErrNone {
+				t.Fatalf("extractSignedHeaders failed: %v", errCode)
+			}
+			actual := getCanonicalHeaders(extracted)
+			if actual != tt.expected {
+				t.Errorf("%s: expected %q, got %q", tt.name, tt.expected, actual)
+			}
+		})
+	}
+}