Connection Refusal as Network Configuration Issue

Monitor for connection timeout errors and validate memcached_backend_current connectivity. Check if memcached_threads shows zero active threads. Correlate with infrastructure logs showing firewall blocks on port 11211 or VPC peering issues.

Verify firewall rules allow traffic on TCP port 11211 between client and Memcached instances. For cloud deployments, ensure VPC peering (e.g., servicenetworking-googleapis-com) is intact. Check that Memcached service is running and listening on expected interface.