Two requests here.

1. Monitoring port should be equal to YT RPC port + 1000.
2. I am almost sure that 9020, 9021 and 9023 are occupied by some other services (maybe through Y internal configuration system). AFAIR, 9020 is a standard port for the discovery servers, therefore there will be a clash of monitoring ports. I'd prefer not to introduce collisions or inconsistencies with the internal Y conventions here, so I suggest choosing higher two ports (rpc and kafka), ideally the same as you already have inside.