There are construction works in Zürich Flughafen (Zurich Airport) station and on the route on whcih Zürich Flughafen lies, which cause some trains to be diverted. It is unfortunately inavoidable to have to change twice, once in Zürich HB (Zurich Main station) and of course in Visp. Note that there is also the just as fast conneciton which changes at Bern instead of Zürich HB. That might be easier if you don’t know Zürich HB as the station of Bern is much simpler to find your way around.