Reduce default MTU for android

experimental/libbox/config.go

@@ -22,6 +22,7 @@ import (
 	"github.com/sagernet/sing/common/logger"
 	"github.com/sagernet/sing/common/x/list"
 	"github.com/sagernet/sing/service"
+	"github.com/sagernet/sing/service/filemanager"
 )
 
 func BaseContext(platformInterface PlatformInterface) context.Context {
@@ -33,7 +34,9 @@ func BaseContext(platformInterface PlatformInterface) context.Context {
 			})
 		}
 	}
-	return box.Context(context.Background(), include.InboundRegistry(), include.OutboundRegistry(), include.EndpointRegistry(), dnsRegistry, include.ServiceRegistry())
+	ctx := context.Background()
+	ctx = filemanager.WithDefault(ctx, sWorkingPath, sTempPath, sUserID, sGroupID)
+	return box.Context(ctx, include.InboundRegistry(), include.OutboundRegistry(), include.EndpointRegistry(), dnsRegistry, include.ServiceRegistry())
 }
 
 func parseConfig(ctx context.Context, configContent string) (option.Options, error) {

experimental/libbox/service.go

@@ -27,7 +27,6 @@ import (
 	"github.com/sagernet/sing/common/logger"
 	N "github.com/sagernet/sing/common/network"
 	"github.com/sagernet/sing/service"
-	"github.com/sagernet/sing/service/filemanager"
 	"github.com/sagernet/sing/service/pause"
 )
 
@@ -44,7 +43,6 @@ type BoxService struct {
 
 func NewService(configContent string, platformInterface PlatformInterface) (*BoxService, error) {
 	ctx := BaseContext(platformInterface)
-	ctx = filemanager.WithDefault(ctx, sWorkingPath, sTempPath, sUserID, sGroupID)
 	service.MustRegister[deprecated.Manager](ctx, new(deprecatedManager))
 	options, err := parseConfig(ctx, configContent)
 	if err != nil {

protocol/tun/inbound.go

@@ -137,6 +137,9 @@ func NewInbound(ctx context.Context, router adapter.Router, logger log.ContextLo
 		if platformInterface != nil && platformInterface.UnderNetworkExtension() {
 			// In Network Extension, when MTU exceeds 4064 (4096-UTUN_IF_HEADROOM_SIZE), the performance of tun will drop significantly, which may be a system bug.
 			tunMTU = 4064
+		} else if C.IsAndroid {
+			// Some Android devices report ENOBUFS when using MTU 65535
+			tunMTU = 9000
 		} else {
 			tunMTU = 65535
 		}