Infrequent resolving issues while installing/updating plex

In most cases (4 of 5 tries) installing/updating plex (plexpass) results in an error while fetching ffmpeg.

root@freenas:~ # iocage upgrade plex
Snapshotting plex...
Updating plugin INDEX...
Running upgrade...

Testing SRV response to iocage-plugins
Testing DNSSEC response to iocage-plugins

Installing plugin packages:
  - multimedia/plexmediaserver...
  - multimedia/ffmpeg...
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/iocage_lib/ioc_plugin.py", line 1255, in __clone_repo
    porcelain.pull(destination, repo_url, errstream=devnull)
  File "/usr/local/lib/python3.6/site-packages/dulwich/porcelain.py", line 802, in pull
    with open_repo_closing(repo) as r:
  File "/usr/local/lib/python3.6/site-packages/dulwich/porcelain.py", line 165, in open_repo_closing
    return closing(Repo(path_or_repo))
  File "/usr/local/lib/python3.6/site-packages/dulwich/repo.py", line 696, in __init__
    "No git repository was found at %(path)s" % dict(path=root)
dulwich.errors.NotGitRepository: No git repository was found at /mnt/MAINRAID/iocage/jails/plex/plugin

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/urllib/request.py", line 1318, in do_open
    encode_chunked=req.has_header('Transfer-encoding'))
  File "/usr/local/lib/python3.6/http/client.py", line 1239, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/local/lib/python3.6/http/client.py", line 1285, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/local/lib/python3.6/http/client.py", line 1234, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/local/lib/python3.6/http/client.py", line 1026, in _send_output
    self.send(msg)
  File "/usr/local/lib/python3.6/http/client.py", line 964, in send
    self.connect()
  File "/usr/local/lib/python3.6/http/client.py", line 1392, in connect
    super().connect()
  File "/usr/local/lib/python3.6/http/client.py", line 936, in connect
    (self.host,self.port), self.timeout, self.source_address)
  File "/usr/local/lib/python3.6/socket.py", line 704, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
  File "/usr/local/lib/python3.6/socket.py", line 745, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno 8] hostname nor servname provided, or not known

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/bin/iocage", line 10, in <module>
    sys.exit(cli())
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/iocage_cli/upgrade.py", line 39, in cli
    ioc.IOCage(jail=jail, skip_jails=True).upgrade(release)
  File "/usr/local/lib/python3.6/site-packages/iocage_lib/iocage.py", line 1862, in upgrade
    new_release = ioc_plugin.IOCPlugin(plugin=uuid).upgrade()
  File "/usr/local/lib/python3.6/site-packages/iocage_lib/ioc_plugin.py", line 1063, in upgrade
    self.update()
  File "/usr/local/lib/python3.6/site-packages/iocage_lib/ioc_plugin.py", line 846, in update
    self.__update_pull_plugin_artifact__(plugin_conf)
  File "/usr/local/lib/python3.6/site-packages/iocage_lib/ioc_plugin.py", line 896, in __update_pull_plugin_artifact__
    self.__clone_repo(plugin_conf['artifact'], f'{path}/plugin')
  File "/usr/local/lib/python3.6/site-packages/iocage_lib/ioc_plugin.py", line 1260, in __clone_repo
    repo_url, destination, errstream=devnull
  File "/usr/local/lib/python3.6/site-packages/dulwich/porcelain.py", line 310, in clone
    progress=errstream.write)
  File "/usr/local/lib/python3.6/site-packages/dulwich/client.py", line 363, in fetch
    progress)
  File "/usr/local/lib/python3.6/site-packages/dulwich/client.py", line 1398, in fetch_pack
    b"git-upload-pack", url)
  File "/usr/local/lib/python3.6/site-packages/dulwich/client.py", line 1282, in _discover_references
    resp, read = self._http_request(url, headers, allow_compression=True)
  File "/usr/local/lib/python3.6/site-packages/dulwich/client.py", line 1261, in _http_request
    resp = self.opener.open(req)
  File "/usr/local/lib/python3.6/urllib/request.py", line 526, in open
    response = self._open(req, data)
  File "/usr/local/lib/python3.6/urllib/request.py", line 544, in _open
    '_open', req)
  File "/usr/local/lib/python3.6/urllib/request.py", line 504, in _call_chain
    result = func(*args)
  File "/usr/local/lib/python3.6/urllib/request.py", line 1361, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "/usr/local/lib/python3.6/urllib/request.py", line 1320, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error [Errno 8] hostname nor servname provided, or not known>

I've checked the network-connection several times. Streaming and other network-related actions work perfectly well.

Kind Regards
Sascha