Added hint text

app/src/main/res/layout/fragment_options_connection.xml

@@ -207,6 +207,18 @@
             app:layout_constraintTop_toBottomOf="@id/swPreferIp4"
             app:switchPadding="12dp" />
 
+        <eu.faircode.email.FixedTextView
+            android:id="@+id/tvTcpKeepAliveHint"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginEnd="48dp"
+            android:text="@string/title_advanced_tcp_keep_alive_hint"
+            android:textAppearance="@style/TextAppearance.AppCompat.Small"
+            android:textStyle="italic"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/swTcpKeepAlive" />
+
         <androidx.appcompat.widget.SwitchCompat
             android:id="@+id/swSslHarden"
             android:layout_width="0dp"
@@ -215,7 +227,7 @@
             android:text="@string/title_advanced_ssl_harden"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/swTcpKeepAlive"
+            app:layout_constraintTop_toBottomOf="@id/tvTcpKeepAliveHint"
             app:switchPadding="12dp" />
 
         <eu.faircode.email.FixedTextView

app/src/main/res/values/strings.xml

@@ -551,6 +551,7 @@
     <string name="title_advanced_metered_hint">Metered connections are generally mobile connections or paid Wi-Fi hotspots</string>
     <string name="title_advanced_metered_warning">Disabling this option will disable receiving and sending messages on mobile internet connections</string>
     <string name="title_advanced_rlah_hint">Assuming no roaming within the EU</string>
+    <string name="title_advanced_tcp_keep_alive_hint">Enabling this can cause connection problems on some devices</string>
     <string name="title_advanced_timeout_hint">The read/write timeout will be set to the double of the connection timeout. Higher values will result in more battery use.</string>
     <string name="title_advanced_ssl_harden_hint">Enabling this will disable weak SSL protocols and ciphers, which can lead to connection problems</string>
     <string name="title_advanced_roaming_hint">Messages headers will always be fetched when roaming. You can use the device\'s roaming setting to disable internet while roaming.</string>