--- a/sys/bus/u4b/serial/ubser.c
+++ b/sys/bus/u4b/serial/ubser.c
@@ -477,8 +477,10 @@ ubser_cfg_set_break(struct ucom_softc *ucom, uint8_t onoff)
 		req.wIndex[1] = 0;
 		USETW(req.wLength, 0);
 
+		/* DF-5515: bound the cfg-path stall -- 250 ms is ample
+		 * for a control request a live adapter serves in <5 ms. */
 		err = ucom_cfg_do_request(sc->sc_udev, ucom, 
-		    &req, NULL, 0, 1000);
+		    &req, NULL, 0, 250);
 		if (err) {
 			DPRINTFN(0, "send break failed, error=%s\n",
 			    usbd_errstr(err));