TCP connection timeout (firewall issue)
Why FTP/SFTP connections time out and how to diagnose firewall, routing, or allowlist blocking.
Diagnose this automatically
Test whether the network port is reachable before investigating authentication problems.
Shareable output
Prefer the browser? Run the same check on the homepage.
A TCP timeout means your request didn’t get a response at all.
This is usually a firewall/security-group block, routing issue, or the service is only reachable from a private network/VPN.
Common causes
- Inbound firewall/security group blocks the port
- Server is private/internal-only (not reachable from the public internet)
- IP allowlist missing your source IP
- Network routing/VPN required
- Upstream device silently drops packets
Fix checklist
- Confirm protocol + port with the vendor/admin.
- Ask the server owner to verify firewall/security-group rules on the server side.
- Check IP allowlist requirements and add your source IP.
- If the host is internal, run checks from inside the network/VPN.
Quick commands
nc -vz <host> <port>
telnet <host> <port>FTPMonitor Help
Still stuck? We can help diagnose and fix it.
Choose the level of help that matches the urgency. Never send passwords, private keys, or other secrets.
Fix Report
$49
A written diagnosis and recommended fix for one FTP, FTPS, or SFTP issue.
- Written diagnosis
- Recommended fix steps
- Best for non-urgent issues
Recommended
Same-Day Help
$149
Priority troubleshooting for one active issue, with a clear same-day diagnosis and action plan.
- Priority troubleshooting
- Same-day diagnosis and action plan
- Best for active business problems
Live Fix Call
$299
Live troubleshooting help for an urgent or unusually complex FTP, FTPS, or SFTP problem.
- Live troubleshooting session
- Best for urgent or complex failures
- Scheduling coordinated after checkout
Related
- TCP connection failed — General TCP failure causes when connecting to FTP, FTPS, or SFTP services.
- DNS resolution failed — Why FTP/SFTP DNS lookups fail and how to fix hostname resolution issues quickly.
Diagnostics powered by FTPMonitor CLI