diff --git a/lib/utils/pref_notifier.dart b/lib/utils/pref_notifier.dart
index a3063bd0..5a6bc761 100644
--- a/lib/utils/pref_notifier.dart
+++ b/lib/utils/pref_notifier.dart
@@ -3,39 +3,52 @@ import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 class PrefNotifier<T> extends AutoDisposeNotifier<T> {
-  PrefNotifier(this._key, this._defaultValue);
+  PrefNotifier(this._key, this._defaultValue, this._mapFrom, this._mapTo);
 
   final String _key;
   final T _defaultValue;
+  final T Function(String)? _mapFrom;
+  final String Function(T)? _mapTo;
 
   static AutoDisposeNotifierProvider<PrefNotifier<T>, T> provider<T>(
     String key,
-    T defaultValue,
-  ) =>
+    T defaultValue, {
+    T Function(String value)? mapFrom,
+    String Function(T value)? mapTo,
+  }) =>
       NotifierProvider.autoDispose(
-        () => PrefNotifier(key, defaultValue),
+        () => PrefNotifier(key, defaultValue, mapFrom, mapTo),
       );
 
   SharedPreferences get _prefs => ref.read(sharedPreferencesProvider);
 
   /// Updates the value asynchronously.
   Future<void> update(T value) async {
-    if (value is String) {
-      await _prefs.setString(_key, value);
-    } else if (value is bool) {
-      await _prefs.setBool(_key, value);
-    } else if (value is int) {
-      await _prefs.setInt(_key, value);
-    } else if (value is double) {
-      await _prefs.setDouble(_key, value);
-    } else if (value is List<String>) {
-      await _prefs.setStringList(_key, value);
+    if (_mapTo != null && _mapFrom != null) {
+      await _prefs.setString(_key, _mapTo!(value));
+    } else {
+      switch (value) {
+        case String _:
+          await _prefs.setString(_key, value);
+        case bool _:
+          await _prefs.setBool(_key, value);
+        case int _:
+          await _prefs.setInt(_key, value);
+        case double _:
+          await _prefs.setDouble(_key, value);
+        case List<String> _:
+          await _prefs.setStringList(_key, value);
+      }
     }
     super.state = value;
   }
 
   @override
   T build() {
+    if (_mapTo != null && _mapFrom != null) {
+      final persisted = _prefs.getString(_key);
+      return persisted != null ? _mapFrom!(persisted) : _defaultValue;
+    }
     return _prefs.get(_key) as T? ?? _defaultValue;
   }
 }
diff --git a/lib/utils/validators.dart b/lib/utils/validators.dart
index fff27f9b..7be7e631 100644
--- a/lib/utils/validators.dart
+++ b/lib/utils/validators.dart
@@ -3,7 +3,16 @@ final _urlRegex = RegExp(
   r"^(?:(?:(?:https?|ftp):)?\/\/)(?:\S+(?::\S*)?@)?(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-z0-9\u00a1-\uffff][a-z0-9\u00a1-\uffff_-]{0,62})?[a-z0-9\u00a1-\uffff]\.)+(?:[a-z\u00a1-\uffff]{2,}\.?))(?::\d{2,5})?(?:[/?#]\S*)?$",
 );
 
+/// https://stackoverflow.com/a/12968117
+final _portRegex = RegExp(
+  r"^([1-9][0-9]{0,3}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$",
+);
+
 /// https://stackoverflow.com/questions/3809401/what-is-a-good-regular-expression-to-match-a-url/3809435#3809435
 bool isUrl(String input) {
   return _urlRegex.hasMatch(input.trim().toLowerCase());
 }
+
+bool isPort(String input) {
+  return _portRegex.hasMatch(input);
+}