Online ping: TCP connection check from Düsseldorf

Online ping: What does this check measure?

This tool makes four TCP connections to the selected public target and port. The default is port 443. Times describe connection setup from our server in Düsseldorf. This is a TCP ping, rather than ICMP echo or a measurement of your Wi-Fi or gaming latency.

How to read the result

• Open: The target port accepted a TCP connection. This does not establish that a website works correctly or has a valid TLS certificate.
• Refused: The connection attempt was rejected. The service may be stopped or the port closed; a firewall can also actively reject a connection.
• Timeout: No connection was established within the limit. Filtering, routing or load may be responsible. The entire host is not necessarily offline.

Min/average/max use successful attempts only. Four brief measurements are a snapshot, not a long-term packet-loss statistic.

Make a useful comparison

Repeat the check with the same hostname, target IP and port. When DNS returns several addresses, select the same address where possible. Compare IPv4 and IPv6 separately. If TCP works but the website fails, try the HTTP availability check. Use traceroute to inspect the observed path.

Read the guide to ping, TCP connection timing and local troubleshooting.