diff --git a/cmd/traefik/traefik.go b/cmd/traefik/traefik.go
index 00683f9fd..8eaf27c72 100644
--- a/cmd/traefik/traefik.go
+++ b/cmd/traefik/traefik.go
@@ -27,6 +27,7 @@ import (
 	"github.com/traefik/traefik/v3/cmd"
 	"github.com/traefik/traefik/v3/cmd/healthcheck"
 	cmdVersion "github.com/traefik/traefik/v3/cmd/version"
+	_ "github.com/traefik/traefik/v3/init"
 	tcli "github.com/traefik/traefik/v3/pkg/cli"
 	"github.com/traefik/traefik/v3/pkg/collector"
 	"github.com/traefik/traefik/v3/pkg/config/dynamic"
diff --git a/init/init.go b/init/init.go
new file mode 100644
index 000000000..e54655d0f
--- /dev/null
+++ b/init/init.go
@@ -0,0 +1,21 @@
+package init
+
+import (
+	"os"
+	"strings"
+)
+
+// This makes use of the GODEBUG flag `http2xconnect` to deactivate the connect setting for HTTP2 by default.
+// This type of upgrade is yet incompatible with `net/http` http1 reverse proxy.
+// Please see https://github.com/golang/go/issues/71128#issuecomment-2574193636.
+func init() {
+	goDebug := os.Getenv("GODEBUG")
+	if strings.Contains(goDebug, "http2xconnect") {
+		return
+	}
+
+	if len(goDebug) > 0 {
+		goDebug += ","
+	}
+	os.Setenv("GODEBUG", goDebug+"http2xconnect=0")
+}