When using the TCP check, some hosts are getting discovered, but the host status switches to offline immediately. Necessary investigation, if hosts are discovered correctly.

Steps to reproduce:

1. Create a discovery rule with TCP check, use any real network and default port. Use short update interval ~ 30s
2. Run server / proxy
3. Review the discovered hosts

Result:
Some discovered hosts have status switched to offline immediately. Possible discovery was triggered incorrectly.

See screenshot: