RPC error: failed to connect to all addresses

Playing around with rebalancelnd and it worked fine through Docker until it didnt.

$ docker run --rm --network=umbrel_main_network -it -v /opt/umbrel/lnd:/root/.lnd rebalancelnd/rebalance-lnd -c --grpc 10.21.21.9:1000

Traceback (most recent call last):
  File "/rebalance-lnd/rebalance.py", line 540, in <module>
    success = main()
  File "/rebalance-lnd/rebalance.py", line 326, in main
    return Rebalance(arguments).start()
  File "/rebalance-lnd/rebalance.py", line 212, in start
    self.list_channels_compact()
  File "/rebalance-lnd/rebalance.py", line 193, in list_channels_compact
    self.lnd.get_channels(active_only=True),
  File "/rebalance-lnd/lnd.py", line 92, in get_channels
    return self.stub.ListChannels(
  File "/usr/local/lib/python3.10/site-packages/grpc/_channel.py", line 946, in __call__
    return _end_unary_response_blocking(state, call, False, None)
  File "/usr/local/lib/python3.10/site-packages/grpc/_channel.py", line 849, in _end_unary_response_blocking
    raise _InactiveRpcError(state)
grpc._channel._InactiveRpcError: <_InactiveRpcError of RPC that terminated with:
	status = StatusCode.UNAVAILABLE
	details = "failed to connect to all addresses"
	debug_error_string = "{"created":"@1642713758.336705688","description":"Failed to pick subchannel","file":"src/core/ext/filters/client_channel/client_channel.cc","file_line":3134,"referenced_errors":[{"created":"@1642713758.336703671","description":"failed to connect to all addresses","file":"src/core/lib/transport/error_utils.cc","file_line":163,"grpc_status":14}]}"

Reboot doesnt help either so the issue seems to persist. Any idea what might be the problem?