diff --git a/Assets/BossRoom/Prefabs/UI/PopupPanel.prefab b/Assets/BossRoom/Prefabs/UI/PopupPanel.prefab
index 20dc6316c..9f7ec8952 100644
--- a/Assets/BossRoom/Prefabs/UI/PopupPanel.prefab
+++ b/Assets/BossRoom/Prefabs/UI/PopupPanel.prefab
@@ -733,7 +733,19 @@ MonoBehaviour:
       m_Calls: []
   m_OnValueChanged:
     m_PersistentCalls:
-      m_Calls: []
+      m_Calls:
+      - m_Target: {fileID: 2699227445768669173}
+        m_TargetAssemblyTypeName: BossRoom.Visual.PopupPanel, BossRoom.Client
+        m_MethodName: SanitizePortText
+        m_Mode: 1
+        m_Arguments:
+          m_ObjectArgument: {fileID: 0}
+          m_ObjectArgumentAssemblyTypeName: UnityEngine.Object, UnityEngine
+          m_IntArgument: 0
+          m_FloatArgument: 0
+          m_StringArgument: 
+          m_BoolArgument: 0
+        m_CallState: 2
   m_CaretColor: {r: 0.19607843, g: 0.19607843, b: 0.19607843, a: 1}
   m_CustomCaretColor: 0
   m_SelectionColor: {r: 0.65882355, g: 0.80784315, b: 1, a: 0.7529412}
@@ -968,7 +980,7 @@ MonoBehaviour:
   m_faceColor:
     serializedVersion: 2
     rgba: 4294967295
-  m_fontSize: 21.55
+  m_fontSize: 18
   m_fontSizeBase: 32
   m_fontWeight: 400
   m_enableAutoSizing: 1
@@ -2069,7 +2081,19 @@ MonoBehaviour:
       m_Calls: []
   m_OnValueChanged:
     m_PersistentCalls:
-      m_Calls: []
+      m_Calls:
+      - m_Target: {fileID: 2699227445768669173}
+        m_TargetAssemblyTypeName: BossRoom.Visual.PopupPanel, BossRoom.Client
+        m_MethodName: SanitizeInputText
+        m_Mode: 1
+        m_Arguments:
+          m_ObjectArgument: {fileID: 0}
+          m_ObjectArgumentAssemblyTypeName: UnityEngine.Object, UnityEngine
+          m_IntArgument: 0
+          m_FloatArgument: 0
+          m_StringArgument: 
+          m_BoolArgument: 0
+        m_CallState: 2
   m_CaretColor: {r: 0.19607843, g: 0.19607843, b: 0.19607843, a: 1}
   m_CustomCaretColor: 0
   m_SelectionColor: {r: 0.65882355, g: 0.80784315, b: 1, a: 0.7529412}
@@ -2637,7 +2661,7 @@ MonoBehaviour:
   m_faceColor:
     serializedVersion: 2
     rgba: 4294967295
-  m_fontSize: 30.35
+  m_fontSize: 35.05
   m_fontSizeBase: 32
   m_fontWeight: 400
   m_enableAutoSizing: 1
diff --git a/Assets/BossRoom/Scripts/Client/UI/PopupPanel.cs b/Assets/BossRoom/Scripts/Client/UI/PopupPanel.cs
index d3da238c6..13ddba261 100644
--- a/Assets/BossRoom/Scripts/Client/UI/PopupPanel.cs
+++ b/Assets/BossRoom/Scripts/Client/UI/PopupPanel.cs
@@ -59,6 +59,8 @@ public class PopupPanel : MonoBehaviour
 
         private const string k_DefaultConfirmText = "OK";
 
+        static readonly char[] k_InputFieldIncludeChars = new[] { '.', '_' };
+
         /// <summary>
         /// Setup this panel to be a panel view to have the player enter the game, complete with the ability for the player to
         /// cancel their input and requests.
@@ -122,6 +124,45 @@ private void OnConfirmClick()
             m_ConfirmFunction.Invoke(m_InputField.text, portNum, m_NameDisplay.GetCurrentName(), (OnlineMode)m_OnlineModeDropdown.value);
         }
 
+        /// <summary>
+        /// Sanitize user port InputField box allowing only alphanumerics, plus any matching chars, if provided.
+        /// </summary>
+        /// <param name="dirtyString"> string to sanitize. </param>
+        /// <param name="includeChars"> Array of chars to include. </param>
+        /// <returns> Sanitized text string. </returns>
+        static string Sanitize(string dirtyString, char[] includeChars = null)
+        {
+            var result = new StringBuilder(dirtyString.Length);
+            foreach (char c in dirtyString)
+            {
+                if (char.IsLetterOrDigit(c) ||
+                    (includeChars != null && Array.Exists(includeChars, includeChar => includeChar == c)))
+                {
+                    result.Append(c);
+                }
+            }
+
+            return result.ToString();
+        }
+
+        /// <summary>
+        /// Added to the InputField component's OnValueChanged callback for the Room/IP UI text.
+        /// </summary>
+        public void SanitizeInputText()
+        {
+            var inputFieldText = Sanitize(m_InputField.text, k_InputFieldIncludeChars);
+            m_InputField.text = inputFieldText;
+        }
+
+        /// <summary>
+        /// Added to the InputField component's OnValueChanged callback for the Port UI text.
+        /// </summary>
+        public void SanitizePortText()
+        {
+            var inputFieldText = Sanitize(m_PortInputField.text);
+            m_PortInputField.text = inputFieldText;
+        }
+
         /// <summary>
         /// Called when the user clicks on the cancel button when in a mode where the player is expecting to input something.
         /// Primary responsibility for this method is to reset the UI state.