thanks - this is my config

systemLog:
  destination: file
  path: /opt/homebrew/var/log/mongodb/mongo.log
  logAppend: true
storage:
  dbPath: /opt/homebrew/var/mongodb
net:
  bindIp: 127.0.0.1
  ipv6: true

I added the ipv6 switch.

I have read that I can also use ::,127.0.0.1 for the bindIp option.
It is supposed to open up the ipv6 resolution to the 127.0.0.1 IP address.