Handshake timed out in cache server

This happened today during a build:

[00:03:32][08be102d][build:flatpak-images/sdk-debug.bst  ] SUCCESS freedesktop-sdk/flatpak-images-sdk-debug/08be102d-build.9671.log
[01:51:55][][] FAILURE Build

Failure Summary
  desktop-image.bst:
    [00:00:20][539a0bec][ push:desktop-image.bst             ] BUG     Push

        An unhandled exception occured:
    
        Traceback (most recent call last):
          File "/root/.local/lib/python3.6/site-packages/buildstream/_scheduler/jobs/job.py", line 415, in _child_action
            result = self.child_process()
          File "/root/.local/lib/python3.6/site-packages/buildstream/_scheduler/jobs/elementjob.py", line 94, in child_process
            return self._action_cb(self._element)
          File "/root/.local/lib/python3.6/site-packages/buildstream/_scheduler/queues/pushqueue.py", line 37, in process
            if not element._push():
          File "/root/.local/lib/python3.6/site-packages/buildstream/element.py", line 1714, in _push
            pushed = self.__artifacts.push(self, self.__get_cache_keys_for_commit())
          File "/root/.local/lib/python3.6/site-packages/buildstream/_artifactcache/cascache.py", line 321, in push
            remote.init()
          File "/root/.local/lib/python3.6/site-packages/buildstream/_artifactcache/cascache.py", line 1015, in init
            response = self.capabilities.GetCapabilities(request)
          File "/usr/local/lib64/python3.6/site-packages/grpc/_channel.py", line 514, in __call__
            return _end_unary_response_blocking(state, call, False, None)
          File "/usr/local/lib64/python3.6/site-packages/grpc/_channel.py", line 448, in _end_unary_response_blocking
            raise _Rendezvous(state, None, None, deadline)
        grpc._channel._Rendezvous: <_Rendezvous of RPC that terminated with:
        	status = StatusCode.UNAVAILABLE
        	details = "Connect Failed"
        	debug_error_string = "{"created":"@1548706034.761381561","description":"Failed to create subchannel","file":"src/core/ext/filters/client_channel/client_channel.cc","file_line":2608,"referenced_errors":[{"created":"@1548706034.761373271","description":"Pick Cancelled","file":"src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc","file_line":234,"referenced_errors":[{"created":"@1548706034.760864621","description":"Connect Failed","file":"src/core/ext/filters/client_channel/subchannel.cc","file_line":663,"grpc_status":14,"referenced_errors":[{"created":"@1548706034.760734330","description":"Handshake read failed","file":"src/core/lib/security/transport/security_handshaker.cc","file_line":321,"referenced_errors":[{"created":"@1548706034.760579333","description":"FD Shutdown","file":"src/core/lib/iomgr/lockfree_event.cc","file_line":190,"referenced_errors":[{"created":"@1548706034.760574053","description":"Handshake timed out","file":"src/core/lib/channel/handshaker.cc","file_line":290}]}]}]}]}]}"
        >

See freedesktop-sdk/freedesktop-sdk#620 (closed)