Why is remote repository sync failing with error 403, message='Forbidden' on Private Automation Hub?

Issue

• Remote repository sync on the Private Automation Hub fails with below error.

  403, message='Forbidden', url=URL('http://proxyserver-FQDN:80')
  Traceback
   File "/usr/lib/python3.9/site-packages/pulpcore/tasking/pulpcore_worker.py", line 458, in _perform_task
  result = func(*args, **kwargs)
    File "/usr/lib/python3.9/site-packages/pulp_ansible/app/tasks/collections.py", line 191, in sync
  repo_version = d_version.create()
    File "/usr/lib/python3.9/site-packages/pulpcore/plugin/stages/declarative_version.py", line 161, in create
  loop.run_until_complete(pipeline)
    File "/usr/lib64/python3.9/asyncio/base_events.py", line 647, in run_until_complete
  return future.result()
    File "/usr/lib/python3.9/site-packages/pulpcore/plugin/stages/api.py", line 220, in create_pipeline
  await asyncio.gather(*futures)
    File "/usr/lib/python3.9/site-packages/pulpcore/plugin/stages/api.py", line 41, in __call__
  await self.run()
    File "/usr/lib/python3.9/site-packages/pulpcore/plugin/stages/artifact_stages.py", line 186, in run
  pb.done += task.result()  # download_count
    File "/usr/lib/python3.9/site-packages/pulpcore/plugin/stages/artifact_stages.py", line 241, in _handle_content_unit
  await asyncio.gather(*downloaders_for_content)
    File "/usr/lib/python3.9/site-packages/pulpcore/plugin/stages/models.py", line 119, in download
  raise e
    File "/usr/lib/python3.9/site-packages/pulpcore/plugin/stages/models.py", line 111, in download
  download_result = await downloader.run(extra_data=self.extra_data)
    File "/usr/lib/python3.9/site-packages/pulpcore/download/http.py", line 273, in run
  return await download_wrapper()
    File "/usr/lib/python3.9/site-packages/backoff/_async.py", line 151, in retry
  ret = await target(*args, **kwargs)
    File "/usr/lib/python3.9/site-packages/pulpcore/download/http.py", line 271, in download_wrapper
  raise e
    File "/usr/lib/python3.9/site-packages/pulpcore/download/http.py", line 258, in download_wrapper
  return await self._run(extra_data=extra_data)
    File "/usr/lib/python3.9/site-packages/pulp_ansible/app/downloaders.py", line 92, in _run
  return await self._run_with_token_refresh_and_401_retry()
    File "/usr/lib/python3.9/site-packages/pulp_ansible/app/downloaders.py", line 110, in _run_with_token_refresh_and_401_retry
  return await self._run_with_additional_headers(headers)
    File "/usr/lib/python3.9/site-packages/pulp_ansible/app/downloaders.py", line 132, in _run_with_additional_headers
  async with self.session.get(
    File "/usr/lib64/python3.9/site-packages/aiohttp/client.py", line 1141, in __aenter__
  self._resp = await self._coro
   File "/usr/lib64/python3.9/site-packages/aiohttp/client.py", line 536, in _request
  conn = await self._connector.connect(
    File "/usr/lib64/python3.9/site-packages/aiohttp/connector.py", line 540, in connect
  proto = await self._create_connection(req, traces, timeout)
    File "/usr/lib64/python3.9/site-packages/aiohttp/connector.py", line 899, in _create_connection
  _, proto = await self._create_proxy_connection(req, traces, timeout)
    File "/usr/lib64/python3.9/site-packages/aiohttp/connector.py", line 1291, in _create_proxy_connection
  raise ClientHttpProxyError(