Colleague experiencing SSH IAP connection error

DevOps Google Cloud
1

One of my colleague is getting this error while trying to ssh through IAP. Firewall rules are good and no issues there.

Traceback (most recent call last):
  File "/opt/homebrew/Caskroom/google-cloud-sdk/520.0.0/google-cloud-sdk/lib/googlecloudsdk/command_lib/compute/iap_tunnel.py", line 775, in RunReceiveLocalData
    websocket_conn = self._InitiateConnection(
                     ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Caskroom/google-cloud-sdk/520.0.0/google-cloud-sdk/lib/googlecloudsdk/command_lib/compute/iap_tunnel.py", line 744, in _InitiateConnection
    new_websocket.InitiateConnection()
  File "/opt/homebrew/Caskroom/google-cloud-sdk/520.0.0/google-cloud-sdk/lib/googlecloudsdk/api_lib/compute/iap_tunnel_websocket.py", line 152, in InitiateConnection
    self._WaitForOpenOrRaiseError()
  File "/opt/homebrew/Caskroom/google-cloud-sdk/520.0.0/google-cloud-sdk/lib/googlecloudsdk/api_lib/compute/iap_tunnel_websocket.py", line 444, in _WaitForOpenOrRaiseError
    raise ConnectionCreationError(error_msg)
googlecloudsdk.api_lib.compute.iap_tunnel_websocket.ConnectionCreationError: Error while connecting [[Errno 50] Network is down].
kex_exchange_identification: Connection closed by remote host
Connection closed by UNKNOWN port 65535```
2

Is your colleague trying to SSH into a GCE VM with internal ONLY ip (no public IP)? What is the command that he is using?