RabbitMQ broker - increase 'channel_max' value - mq.m5.large

Hello,

Our app started to fail due to not being able to create new channels. According to this https://docs.aws.amazon.com/amazon-mq/latest/developer-guide/rabbitmq-sizing-guidelines.html the large instance should be able to handle 15000 channels, but it seems that it currently uses 2047 (RabbitMQ's default setting) and cannot be changed. We tried to override it through the configuration, but the configuration gets updated and the channel_max is removed (it says that channel_max is unsupported element).

We have a single node broker of mq.m5.large size. We configured our app to request 5000 channels (locally it works).

What I am missing? Any input is appreciated. Thank you in advance.