Change default DNS to Quad9 and MTU to 1500

Merge PR #36: update fresh-install defaults for DNS and MTU.

Author: hawkff

app/src/main/java/io/nekohasekai/sagernet/database/DataStore.kt

@@ -109,7 +109,7 @@ object DataStore : OnPreferenceDataStoreChangeListener {
     var trafficSniffing by configurationStore.stringToInt(Key.TRAFFIC_SNIFFING) { 1 }
     var resolveDestination by configurationStore.boolean(Key.RESOLVE_DESTINATION)
 
-    var mtu by configurationStore.stringToInt(Key.MTU) { 9000 }
+    var mtu by configurationStore.stringToInt(Key.MTU) { 1500 }
 
     var bypassLan by configurationStore.boolean(Key.BYPASS_LAN)
     var bypassLanInCore by configurationStore.boolean(Key.BYPASS_LAN_IN_CORE)
@@ -125,8 +125,8 @@ object DataStore : OnPreferenceDataStoreChangeListener {
 
     var globalCustomConfig by configurationStore.string(Key.GLOBAL_CUSTOM_CONFIG) { "" }
 
-    var remoteDns by configurationStore.string(Key.REMOTE_DNS) { "https://dns.google/dns-query" }
-    var directDns by configurationStore.string(Key.DIRECT_DNS) { "https://223.5.5.5/dns-query" }
+    var remoteDns by configurationStore.string(Key.REMOTE_DNS) { "https://dns.quad9.net/dns-query" }
+    var directDns by configurationStore.string(Key.DIRECT_DNS) { "https://1.1.1.1/dns-query" }
     var enableDnsRouting by configurationStore.boolean(Key.ENABLE_DNS_ROUTING) { true }
     var enableFakeDns by configurationStore.boolean(Key.ENABLE_FAKEDNS) { true }
 

app/src/main/res/xml/global_preferences.xml

@@ -45,7 +45,7 @@
             app:title="@string/tun_implementation"
             app:useSimpleSummaryProvider="true" />
         <moe.matsuri.nb4a.ui.MTUPreference
-            app:defaultValue="9000"
+            app:defaultValue="1500"
             app:entries="@array/mtu_select"
             app:entryValues="@array/mtu_select"
             app:icon="@drawable/baseline_public_24"
@@ -195,7 +195,7 @@
 
     <PreferenceCategory app:title="@string/cag_dns">
         <EditTextPreference
-      app:defaultValue="https://dns.google/dns-query"
+      app:defaultValue="https://dns.quad9.net/dns-query"
             app:icon="@drawable/ic_action_dns"
             app:key="remoteDns"
             app:title="@string/remote_dns"
@@ -208,7 +208,7 @@
             app:title="@string/domain_strategy_for_remote"
             app:useSimpleSummaryProvider="true" />
         <EditTextPreference
-            app:defaultValue="https://223.5.5.5/dns-query"
+            app:defaultValue="https://1.1.1.1/dns-query"
             app:icon="@drawable/ic_action_dns"
             app:key="directDns"
             app:title="@string/direct_dns"