Network and server guides

Practical guides to port forwarding, DNS records, TLS certificates, and HTTP status codes. Understand the results and decide what to check next.

Connection problems

Port troubleshooting Before changing forwarding rules, compare the target IP, listening address, LAN access and NAT path. Each step separates what you have verified from what remains unknown. Port forwarding guide Forward an external IPv4 connection to a server behind your router. Check each part of the path in order.

Domain & HTTPS problems

DNS record types Understand address, alias, mail, and text records. Check the record name separately from its value. TLS certificate guide Read certificate names, dates, and verification results. Confirm that a renewed certificate is actually being served. HTTP status codes Read a status code in context. Compare the URL, request method, and logs before deciding what failed.

Address & port basics

Private and special IP ranges Distinguish private, shared, loopback, and link-local addresses. Interpret IPv4 WAN comparisons separately from IPv6. Common network ports Match the service and transport protocol to its configured port. A familiar port number does not establish what is running or whether exposure is safe.