gRPC mac comand connection warning 'read: connection reset by peer'

time="2021-12-13T09:03:40.641780416Z" level=info msg="mac-command queue item created" cid=LinkADRReq ctx_id=343a0b7d-1726-4790-b651-20c8df39b024 dev_eui=3bc1efb6e719cc2c
time="2021-12-13T09:03:40.641850415Z" level=info msg="finished unary call with code OK" ctx_id=343a0b7d-1726-4790-b651-20c8df39b024 grpc.code=OK grpc.method=CreateMACCommandQueueItem grpc.service=ns.NetworkServerService grpc.start_time="2021-12-13T09:03:40Z" grpc.time_ms=1.583 peer.address="114.221.231.104:17817" span.kind=server system=grpc
time="2021-12-13T09:03:40.654510203Z" level=warning msg="[transport] transport: http2Server.HandleStreams failed to read frame: read tcp 172.18.0.5:8000->114.221.231.104:17817: read: connection reset by peer"

What is ‘read: connection reset by peer’? I think there may be some problem with firewall.

It means it hit a closed port.

But I indeed opened the port 8000.
When I open the port ‘17817’, it report another warning:

time="2021-12-14T02:04:38.003729151Z" level=warning msg="[transport] transport: http2Server.HandleStreams failed to read frame: read tcp 172.18.0.5:8000->114.221.231.104:19868: read: connection reset by peer"

I think the latter port is random.