Unable to execute multiple cycles (Message send failed, try 1 of 7: Cannot connect:)

cylc version 7.8.X
moved suites to new hpc machine.
first cycle completes, but then

WARNING - Message send failed, try 1 of 7: Cannot connect: [https://MACHINE.hpc.mil:43025/put_messages:](https://MACHINE.hpc.mil/put_messages:) HTTPSConnectionPool(host=MACHINE.hpc.mil', port=43025): Max retries exceeded with url: /put_messages (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x14b7c9a88e10>: Failed to establish a new connection: [Errno -2] Name or service not known',))

suspect issue with ‘hostname’ or something of that ilk.
suggestions welcome.

Did the task jobs in the first cycle also run on the new machine?

The job error simply indicates that the scheduler host is not reachable from the job host, via the URL above, for job status messaging. That normally means you need system admins to tweak network settings to allow communications between those hosts, for the configured Cylc ports. But if that hasn’t been done, the first cycle tasks should have had the same problem, if they ran on the same host.