diff --git a/Duplicati/Library/Backend/AlternativeFTP/AlternativeFTPBackend.cs b/Duplicati/Library/Backend/AlternativeFTP/AlternativeFTPBackend.cs
index 7e5a89c92..e8cd77335 100644
--- a/Duplicati/Library/Backend/AlternativeFTP/AlternativeFTPBackend.cs
+++ b/Duplicati/Library/Backend/AlternativeFTP/AlternativeFTPBackend.cs
@@ -29,6 +29,7 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Net;
 using System.Net.Security;
 using System.Security.Authentication;
 using System.Threading;
@@ -47,7 +48,7 @@ namespace Duplicati.Library.Backend.AlternativeFTP
 
         private const FtpDataConnectionType DEFAULT_DATA_CONNECTION_TYPE = FtpDataConnectionType.AutoPassive;
         private const FtpEncryptionMode DEFAULT_ENCRYPTION_MODE = FtpEncryptionMode.None;
-        private const SslProtocols DEFAULT_SSL_PROTOCOLS = SslProtocols.Default;
+        private static readonly SslProtocols DEFAULT_SSL_PROTOCOLS = SslProtocols.None; // NOTE: None means "use system default"
         private const string CONFIG_KEY_AFTP_ENCRYPTION_MODE = "aftp-encryption-mode";
         private const string CONFIG_KEY_AFTP_DATA_CONNECTION_TYPE = "aftp-data-connection-type";
         private const string CONFIG_KEY_AFTP_SSL_PROTOCOLS = "aftp-ssl-protocols";
@@ -100,7 +101,7 @@ namespace Duplicati.Library.Backend.AlternativeFTP
         {
             get
             {
-                return new List<ICommandLineArgument>(new ICommandLineArgument[] {
+                return new List<ICommandLineArgument>([
                           new CommandLineArgument("auth-password", CommandLineArgument.ArgumentType.Password, Strings.DescriptionAuthPasswordShort, Strings.DescriptionAuthPasswordLong),
                           new CommandLineArgument("auth-username", CommandLineArgument.ArgumentType.String, Strings.DescriptionAuthUsernameShort, Strings.DescriptionAuthUsernameLong),
                           new CommandLineArgument("disable-upload-verify", CommandLineArgument.ArgumentType.Boolean, Strings.DescriptionDisableUploadVerifyShort, Strings.DescriptionDisableUploadVerifyLong),
@@ -110,7 +111,7 @@ namespace Duplicati.Library.Backend.AlternativeFTP
                           new CommandLineArgument(CONFIG_KEY_AFTP_UPLOAD_DELAY, CommandLineArgument.ArgumentType.Timespan, Strings.DescriptionUploadDelayShort, Strings.DescriptionUploadDelayLong, DEFAULT_UPLOAD_DELAY_STRING),
                           new CommandLineArgument(CONFIG_KEY_AFTP_LOGTOCONSOLE, CommandLineArgument.ArgumentType.Boolean, Strings.DescriptionLogToConsoleShort, Strings.DescriptionLogToConsoleLong),
                           new CommandLineArgument(CONFIG_KEY_AFTP_LOGPRIVATEINFOTOCONSOLE, CommandLineArgument.ArgumentType.Boolean, Strings.DescriptionLogPrivateInfoToConsoleShort, Strings.DescriptionLogPrivateInfoToConsoleLong, "false"),
-                     });
+                     ]);
             }
         }
 
@@ -184,10 +185,8 @@ namespace Duplicati.Library.Backend.AlternativeFTP
             }
 
             // Process the aftp-encryption-mode option
-            string encryptionModeString;
             FtpEncryptionMode encryptionMode;
-
-            if (!options.TryGetValue(CONFIG_KEY_AFTP_ENCRYPTION_MODE, out encryptionModeString) || string.IsNullOrWhiteSpace(encryptionModeString))
+            if (!options.TryGetValue(CONFIG_KEY_AFTP_ENCRYPTION_MODE, out var encryptionModeString) || string.IsNullOrWhiteSpace(encryptionModeString))
             {
                 encryptionModeString = null;
             }
@@ -198,10 +197,8 @@ namespace Duplicati.Library.Backend.AlternativeFTP
             }
 
             // Process the aftp-ssl-protocols option
-            string sslProtocolsString;
             SslProtocols sslProtocols;
-
-            if (!options.TryGetValue(CONFIG_KEY_AFTP_SSL_PROTOCOLS, out sslProtocolsString) || string.IsNullOrWhiteSpace(sslProtocolsString))
+            if (!options.TryGetValue(CONFIG_KEY_AFTP_SSL_PROTOCOLS, out var sslProtocolsString) || string.IsNullOrWhiteSpace(sslProtocolsString))
             {
                 sslProtocolsString = null;
             }
@@ -473,7 +470,7 @@ namespace Duplicati.Library.Backend.AlternativeFTP
                 }
                 catch (Exception e)
                 {
-                    if (e.InnerException != null) { e =  e.InnerException; }
+                    if (e.InnerException != null) { e = e.InnerException; }
                     throw new Exception(string.Format(Strings.ErrorDeleteFile, e.Message), e);
                 }
             }