diff --git a/package/network/utils/comgt/files/ncm.sh b/package/network/utils/comgt/files/ncm.sh
index f5bed7d5e1..6545091c82 100644
--- a/package/network/utils/comgt/files/ncm.sh
+++ b/package/network/utils/comgt/files/ncm.sh
@@ -74,7 +74,7 @@ proto_ncm_setup() {
 	[ -n "$delay" ] && sleep "$delay"
 
 	manufacturer=$(gcom -d "$device" -s /etc/gcom/getcardinfo.gcom | awk 'NF && $0 !~ /AT\+CGMI/ { sub(/\+CGMI: /,""); print tolower($1); exit; }')
-	[ $? -ne 0 ] && {
+	[ $? -ne 0 -o -z "$manufacturer" ] && {
 		echo "Failed to get modem information"
 		proto_notify_error "$interface" GETINFO_FAILED
 		return 1
@@ -88,6 +88,7 @@ proto_ncm_setup() {
 		proto_set_available "$interface" 0
 		return 1
 	}
+
 	json_get_values initialize initialize
 	for i in $initialize; do
 		eval COMMAND="$i" gcom -d "$device" -s /etc/gcom/runcommand.gcom || {
@@ -119,22 +120,26 @@ proto_ncm_setup() {
 	[ -n "$mode" ] && {
 		json_select modes
 		json_get_var setmode "$mode"
-		echo "Setting mode"
-		eval COMMAND="$setmode" gcom -d "$device" -s /etc/gcom/runcommand.gcom || {
-			echo "Failed to set operating mode"
-			proto_notify_error "$interface" SETMODE_FAILED
-			return 1
+		[ -n "$setmode" ] && {
+			echo "Setting mode"
+			eval COMMAND="$setmode" gcom -d "$device" -s /etc/gcom/runcommand.gcom || {
+				echo "Failed to set operating mode"
+				proto_notify_error "$interface" SETMODE_FAILED
+				return 1
+			}
 		}
 		json_select ..
 	}
 
 	echo "Starting network $interface"
 	json_get_vars connect
-	echo "Connecting modem"
-	eval COMMAND="$connect" gcom -d "$device" -s /etc/gcom/runcommand.gcom || {
-		echo "Failed to connect"
-		proto_notify_error "$interface" CONNECT_FAILED
-		return 1
+	[ -n "$connect" ] && {
+		echo "Connecting modem"
+		eval COMMAND="$connect" gcom -d "$device" -s /etc/gcom/runcommand.gcom || {
+			echo "Failed to connect"
+			proto_notify_error "$interface" CONNECT_FAILED
+			return 1
+		}
 	}
 
 	json_get_vars finalize
@@ -182,7 +187,6 @@ proto_ncm_setup() {
 			return 1
 		}
 	}
-
 }
 
 proto_ncm_teardown() {
@@ -195,6 +199,20 @@ proto_ncm_teardown() {
 
 	[ -n "$ctl_device" ] && device=$ctl_device
 
+	[ -n "$device" ] || {
+		echo "No control device specified"
+		proto_notify_error "$interface" NO_DEVICE
+		proto_set_available "$interface" 0
+		return 1
+	}
+
+	device="$(readlink -f $device)"
+	[ -e "$device" ] || {
+		echo "Control device not valid"
+		proto_set_available "$interface" 0
+		return 1
+	}
+
 	[ -n "$profile" ] || profile=1
 
 	echo "Stopping network $interface"
@@ -202,6 +220,16 @@ proto_ncm_teardown() {
 	json_load "$(ubus call network.interface.$interface status)"
 	json_select data
 	json_get_vars manufacturer
+	[ $? -ne 0 -o -z "$manufacturer" ] && {
+		# Fallback to direct detect, for proper handle device replug.
+		manufacturer=$(gcom -d "$device" -s /etc/gcom/getcardinfo.gcom | awk 'NF && $0 !~ /AT\+CGMI/ { sub(/\+CGMI: /,""); print tolower($1); exit; }')
+		[ $? -ne 0 -o -z "$manufacturer" ] && {
+			echo "Failed to get modem information"
+			proto_notify_error "$interface" GETINFO_FAILED
+			return 1
+		}
+		json_add_string "manufacturer" "$manufacturer"
+	}
 
 	json_load "$(cat /etc/gcom/ncm.json)"
 	json_select "$manufacturer" || {
@@ -211,10 +239,12 @@ proto_ncm_teardown() {
 	}
 
 	json_get_vars disconnect
-	eval COMMAND="$disconnect" gcom -d "$device" -s /etc/gcom/runcommand.gcom || {
-		echo "Failed to disconnect"
-		proto_notify_error "$interface" DISCONNECT_FAILED
-		return 1
+	[ -n "$disconnect" ] && {
+		eval COMMAND="$disconnect" gcom -d "$device" -s /etc/gcom/runcommand.gcom || {
+			echo "Failed to disconnect"
+			proto_notify_error "$interface" DISCONNECT_FAILED
+			return 1
+		}
 	}
 
 	proto_init_update "*" 0