Connection Refused vs Connection Timed Out vs Reset (Fix Guide)
Fix connection refused (TCP RST), connection timed out, and connection reset errors. Step-by-step diagnostic checklist to test ports, firewalls, and servers.
How to Check if a Port Is Open: Windows, Mac, Linux & Online
Test if a TCP port is open online with our free port checker, or run nc, nmap, telnet, and Test-NetConnection locally on Windows, macOS, and Linux.
Server Monitoring Basics: Uptime, Reachability, and Response Checks
Build server monitoring in layers: host telemetry, ICMP where useful, private or public TCP checks, HTTP correctness, TLS, jobs, and response-time SLIs.
TCP Port Monitoring: Reachability, Alerts, and Service Health
Use TCP port monitoring to detect listener, firewall, routing, and handshake failures, then pair it with protocol checks that prove the service works.