One medium size bus leaves once (or twice?) daily. Around 1 or 2 pm… (verify)
Next to Jose Luis supermarket, on main hwy thru pp, same side of street as Jose Luis, (on west side of market), a small unmarked stop, in front of/next to a electrodoméstico store (DS something), usually couple people out front, around 400 pesos one-way to LS, approx 4 hr one way.
(Do not take the smaller “Río San Juan-PP” bus)