Lost connection to service

Hello everyone, I have docker swarm 19.03.2, 5 masters, 25 workers. 2 services are running, each service has 7 replicas. If you enter the container of the first service,
and check 2 service nc -vz service 8080 several times, then at some point the connection does not reach, Host is unreachable. Only a full reboot of the entire docker swarm helps. Tell me how to identify the cause?

You run 14 containers on 25 nodes?

What is the behavior of your containers, are they up permanently and healthy?

You could check the daemon logs for hints: