Laravel Vapor reaching limits with Queue and not clear what a solution can be

I'm new to Serverless hosting on AWS. I configured a working serverless environment via Laravel Vapor, but with some issues on a high load.

A high load is 10k requests within seconds, all doing a change in the database.

I use a PostgreSQL-database instance (db.t3.micro) now, not the Serverless version and found out there is some limitation of requests is can handle: “SQLSTATE[08006] [7] FATAL: remaining connection slots are reserved for non-replication superuser connections”

How can I solve this? Replacing it with a Serverless instance or scale the Fixed-size PostgreSQL?

And is the Queue by itself serverless or can I assign more memory to the queue specificly? Or is that combined with the memory the instance itself gets?

This is currently the Vapor.yml-file

id: ---
name: foobar-***
separate-vendor: true
environments:
  staging:
    warm: 10
    scheduler: false
    timeout: 60
    memory: 1024
    queue-memory: 2048
    cli-memory: 512
    cache: serverless
    database: “database-***"
    max_connections: 10000
    balancer: “**-balancer"
    runtime: php-7.4
    build:
      - "COMPOSER_MIRROR_PATH_REPOS=1 composer install"
      - "php artisan event:cache"
      - "php artisan migrate --force"
    domain: "*.domain.app"

This error relates to your maximum connections on your database.

Call show max_connections; to see what this limit is. For t3.micro this would be 112 looking at the AWS documentation.

This would automatically increase with a larger DB instance, however you could just override the parameter in the Parameter Group assigned to the RDS instance.

Change the one called max_connctions till you find a number that is suitable to you.