max_connections parameter: too_many_connections error

*Hello*,

We are working on a payments systems which uses postgreSql 9.6 as backend
DB and blockchain technology. The database is setup in HA in master-standby
mode using pacemaker on Linux 7.6.

*We are new to postgres and ne*ed help in deciding how to set value for
max_connections on DB.

1. How can we decide on optimal value for max_connections for a given
setup/server? I checked many posts saying that even 1000 is considered as a
very high value but we are hitting the error too_many_connections due to
Max_connections value limit.

2. We usee hikari pool on the client side but that even has limitations.
Implementing pg_bouncer is another suggestion in the posts. In a HA setup,
do we have to set it up on both primary standby?

Please provide your advice/suggestions.

Thanks.