The Royal Plazza Hotel is 10 min walk from Montreux train station
Train is the easiest way to circulate in Switzerland.
Travelling by train from Geneva airport to Montreux:
https://www.thetrainline.com/en/train-times/geneva-airport-to-montreux
Travelling by train from Zurich to Montreux:
https://www.omio.com/trains/zurich-airport/geneva-international-airport-c2ial?gclid=Cj0KCQiA4uCcBhDdARIsAH5jyUnm9pGCf7bzuZVKjq2vEAgfebF2wffm4IuXlLBA1WPOr03NMQepYYwaAu5REALw_wcB
Montreux rail station