Jazz in Montreux?

I don't know of any on top of my head. However, I suggest looking up Google Maps by simply typing "jazz club" in the search box. Start from there and read the reviews of the resultant establishments.

There’s a jazz café listed on the Montreux tourism site:

https://www.montreuxriviera.com/en/P5159/montreux-jazz-cafe

Google is the answer here, or ask your hotel. Or call a big hotel and tell them you're going to be visiting and ask for a recommendations. Even though they have a world-famous festival, they may not have many clubs in between.

Back in 2017 we attended the final day of the Montreux Jazz Festival and the music on the free stages was more European techno than jazz. The town has a beautiful waterfront promenade and is well worth visiting! Sorry I don't have any club recommendations.