diff --git a/test/box_test.go b/test/box_test.go
index 4ce61d468..4092979ff 100644
--- a/test/box_test.go
+++ b/test/box_test.go
@@ -86,7 +86,7 @@ func testSuitLargeUDP(t *testing.T, clientPort uint16, testPort uint16) {
 	require.NoError(t, testPingPongWithPacketConn(t, testPort, dialUDP))
 	require.NoError(t, testLargeDataWithConn(t, testPort, dialTCP))
 	require.NoError(t, testLargeDataWithPacketConn(t, testPort, dialUDP))
-	require.NoError(t, testLargeDataWithPacketConnSize(t, testPort, 1250, dialUDP))
+	require.NoError(t, testLargeDataWithPacketConnSize(t, testPort, 5000, dialUDP))
 }
 
 func testTCP(t *testing.T, clientPort uint16, testPort uint16) {
diff --git a/test/config/tuic-client.json b/test/config/tuic-client.json
index 254fba806..0db1755ce 100644
--- a/test/config/tuic-client.json
+++ b/test/config/tuic-client.json
@@ -9,7 +9,8 @@
     ]
   },
   "local": {
-    "server": "127.0.0.1:10001"
+    "server": "127.0.0.1:10001",
+    "max_packet_size": 65535
   },
   "log_level": "debug"
 }
\ No newline at end of file
diff --git a/test/config/tuic-server.json b/test/config/tuic-server.json
index 74e83eba7..4907796ba 100644
--- a/test/config/tuic-server.json
+++ b/test/config/tuic-server.json
@@ -5,5 +5,6 @@
     },
     "certificate":  "/etc/tuic/cert.pem",
     "private_key": "/etc/tuic/key.pem",
+    "max_external_packet_size": 65535,
     "log_level": "debug"
 }
\ No newline at end of file