diff --git a/src/south/Modbus/Modbus.class.js b/src/south/Modbus/Modbus.class.js
index 3db2eafe74..8b9842eddc 100644
--- a/src/south/Modbus/Modbus.class.js
+++ b/src/south/Modbus/Modbus.class.js
@@ -66,12 +66,12 @@ class Modbus extends SouthConnector {
         async () => this.modbusFunction(point),
       ), Promise.resolve())
     } catch (error) {
-      if (error?.err === 'Offline') {
+      if (error.err === 'Offline') {
         this.logger.error('Modbus server offline.')
         await this.disconnect()
         this.reconnectTimeout = setTimeout(this.connect.bind(this), this.retryInterval)
       } else {
-        throw error
+        throw new Error(error.err)
       }
     }
   }
diff --git a/src/south/Modbus/Modbus.class.spec.js b/src/south/Modbus/Modbus.class.spec.js
index fe02184832..01022ba982 100644
--- a/src/south/Modbus/Modbus.class.spec.js
+++ b/src/south/Modbus/Modbus.class.spec.js
@@ -226,7 +226,9 @@ describe('South Modbus', () => {
   it('should throw error if modbus function throws an error', async () => {
     await south.connect()
     south.client.readHoldingRegisters = jest.fn().mockImplementation(() => {
-      throw new Error('modbus error')
+      const rejectError = new Error()
+      rejectError.err = 'modbus error'
+      throw rejectError
     })
     let modbusError
     try {
diff --git a/src/south/SouthConnector.class.js b/src/south/SouthConnector.class.js
index 653f607f3b..937fa0c03c 100644
--- a/src/south/SouthConnector.class.js
+++ b/src/south/SouthConnector.class.js
@@ -324,6 +324,10 @@ class SouthConnector {
   async disconnect() {
     this.connected = false
     const { name, id } = this.settings
+    Object.keys(this.currentlyOnScan).forEach((scanMode) => {
+      this.currentlyOnScan[scanMode] = 0
+      this.queryParts[scanMode] = 0
+    })
     this.statusService.updateStatusDataStream({ 'Connected at': 'Not connected' })
     this.logger.info(`South connector "${name}" (${id}) disconnected.`)
   }