Zowe externalPort does not open

[outtheresomewhere]

Zowe 2.7 on z/OS V2R5. Server starts with this zwe command:

_******zwe start --config /global/zowe/zowe.yaml**       
                                  
Temporary directory '/tmp/.zweenv-586' created.                                                        
**Zowe will remove it on success, but if zwe exits with a non-zero code manual cleanup would be needed.**  
===============================================================================                        
>> STARTING ZOWE                                                                                       
                                                                                                       
-------------------------------------------------------------------------------                        
>> Job ZWE1SV is started successfully.                                                                 
                                                                                                       
Temporary directory /tmp/.zweenv-586 removed successfully.****_  

but the externalPort specified in the yaml file, port 7554, does not open. When I try to connect to access the Zowe Desktop from a Windows 11 client, I get 'connection refused'. Port 7554 is NOT open. This Windows Powershell command:

tnc sitename -port 7554

returns this:

ComputerName           : sitename.com
RemoteAddress          : xx.xx.xx.xx
RemotePort             : 7554
InterfaceAlias         : Wi-Fi
SourceAddress          : 192.168.0.9
PingSucceeded          : True
PingReplyDetails (RTT) : 28 ms
TcpTestSucceeded       : False_                                        

Can someone give me a hint on how to debug this? I have debug: true set in all possible places in the yaml file but no error messages are appearing in the server log to indicate why connections to port 7554 are refused.

I have attached my zowe.yaml file with DNS name and IP addresses sanitized.

zowe.yaml.txt

[achmelo]

Could you please make sure that Gateway service is running? You should see a message that starts with "ZWEAM000I Gateway Service started in".

[outtheresomewhere]

No ZWEAM000I message appears. The yaml file is parsed (clean) and then I see an unending series of this message issued over and over:

JSON: write error, rc -1, return code 0, reason code 00000000

which is pretty much useless, since the message does NOT indicate which file or directory the write error occurred on.

Is this a file or directory permissions error?