From 410bd341fa3c82fcdfa502956cd7fc5ba5dae088 Mon Sep 17 00:00:00 2001
From: Jamil <jamilbk@users.noreply.github.com>
Date: Wed, 13 Dec 2023 13:00:48 -0800
Subject: [PATCH] Set the MTU to 1280 on Apple to avoid connectivity issues
 (#2901)

Unfortunately tunnelOverheadBytes isn't a reliable way to calculate the
MTU.

This could be the issue behind #2855
---
 .../apple/FirezoneNetworkExtension/NetworkSettings.swift  | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/swift/apple/FirezoneNetworkExtension/NetworkSettings.swift b/swift/apple/FirezoneNetworkExtension/NetworkSettings.swift
index 2f917af0b..41ba898e4 100644
--- a/swift/apple/FirezoneNetworkExtension/NetworkSettings.swift
+++ b/swift/apple/FirezoneNetworkExtension/NetworkSettings.swift
@@ -34,8 +34,10 @@ class NetworkSettings {
   let tunnelAddressIPv6: String
   let dnsAddress: String
 
-  // WireGuard has an 80-byte overhead.
-  let tunnelOverheadBytes = NSNumber(80)
+  // WireGuard has an 80-byte overhead. We could try setting tunnelOverheadBytes
+  // but that's not a reliable way to calculate how big our packets should be,
+  // so just use the minimum.
+  let mtu: NSNumber = 1280
 
   // Modifiable values
   private(set) var dnsFallbackStrategy: DNSFallbackStrategy
@@ -181,7 +183,7 @@ class NetworkSettings {
       dnsSettings.matchDomains = [""]
     }
     tunnelNetworkSettings.dnsSettings = dnsSettings
-    tunnelNetworkSettings.tunnelOverheadBytes = tunnelOverheadBytes
+    tunnelNetworkSettings.mtu = mtu
 
     self.hasUnappliedChanges = false
     logger.log("Attempting to set network settings")