Linux VDA cannot register to DDC.
VDA log:
[2023/06/14 10:30:47.5774031] [BrokerAgent] [Error] AttemptRegistrationWithSingleDdc: Registration with 'DDC_FQDN @ DDC_IP' failed. RejectionCode='AgentNotContactable'
[2023/06/14 10:30:47.5802951] [BrokerAgentAoTracing] [Error] REGISTRATION Failed registration: VDA machine SID: S-1-5-21-3777058018-2983854656-4204807762-61483, Broker: DDC_FQDN @ DDC_IP, Heartbeat period: 0 Error: AgentNotContactable

DDC log:
2023/06/14 15:53:21:57582,105236,1740,1,BrokerComponent,,0,,1,Error,"[TID:87d157f8-0a88-11ee-9c1a-835cddbebebe]TestWorkerCommsCBP1_5 failed for worker S-1-5-21-xxxxxxxxxxxxxxxxxxx caught exception: System.ServiceModel.EndpointNotFoundException: There was no endpoint listening at http://VDA_IP/Citrix/VirtualDesktopAgent/IQueryAgent  This is usually caused by an incorrect address or SOAP operation. If this is the case, see InnerException for details. ---> System.Net.WebException: Remote Server Returned 404

 

Problem Cause

Command "netstat -tupln" shows that Port 80 on the Linux VDA is occupied by Ngnix process.