diff --git a/supervisor/supervisor.lua b/supervisor/supervisor.lua
index a90693d..96d2c98 100644
--- a/supervisor/supervisor.lua
+++ b/supervisor/supervisor.lua
@@ -105,11 +105,11 @@ function supervisor.load_config()
     cfv.assert((config.WirelessModem == true) or (type(config.WiredModem) == "string"))
 
     cfv.assert_type_int(config.PLC_Listen)
-    cfv.assert_range(config.PLC_Listen, 0, 2)
+    cfv.assert_range(config.PLC_Listen, 1, 3)
     cfv.assert_type_int(config.RTU_Listen)
-    cfv.assert_range(config.RTU_Listen, 0, 2)
+    cfv.assert_range(config.RTU_Listen, 1, 3)
     cfv.assert_type_int(config.CRD_Listen)
-    cfv.assert_range(config.CRD_Listen, 0, 2)
+    cfv.assert_range(config.CRD_Listen, 1, 3)
 
     cfv.assert_type_bool(config.PocketEnabled)
     cfv.assert_type_bool(config.PocketTest)