As long as our instructions from Configuring macOS for Remote Access are followed carefully, it’s uncommon for a technical issue to prevent local-network connections. Your first step, then, is to double-check those instructions for possible mistakes during set-up.
We also advise to reset the Remote Management service as it could break after some event or a macOS update for unknown reasons.
If you’re still unable to connect, please reproduce the issue and send a diagnostics report. We’ll be happy to review the information and offer any help we can.