Unable to get plugins

[rikingcn]

Error: Traceback (most recent call last):
File "/usr/local/lib/python3.6/site-packages/middlewared/main.py", line 166, in call_method
result = await self.middleware.call_method(self, message)
File "/usr/local/lib/python3.6/site-packages/middlewared/main.py", line 1093, in call_method
return await self._call(message['method'], serviceobj, methodobj, params, app=app, io_thread=False)
File "/usr/local/lib/python3.6/site-packages/middlewared/main.py", line 1037, in _call
return await self._call_worker(name, *args)
File "/usr/local/lib/python3.6/site-packages/middlewared/main.py", line 1058, in call_worker
return await self.run_in_proc(main_worker, name, args, job)
File "/usr/local/lib/python3.6/site-packages/middlewared/main.py", line 990, in run_in_proc
return await async_run_in_executor(loop, executor, method, *args, **kwargs)
File "/usr/local/lib/python3.6/site-packages/middlewared/utils/asyncio.py", line 41, in async_run_in_executor
raise result
RuntimeError: Cmd('git') failed due to: exit code(128)
cmdline: git clone -v https://github.com/freenas/iocage-ix-plugins.git /mnt/cache/iocage/.plugin_index
stderr: 'Cloning into '/mnt/cache/iocage/.plugin_index'...
fatal: unable to access 'https://github.com/freenas/iocage-ix-plugins.git/': OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to github.com:443

Please help me solve this pending problem? thank you