Direct answer
YAML depends on spaces, indentation and list markers. Use spaces instead of tabs, keep comments outside values, and validate after every manual edit.
What to check first
Rules, DNS and TUN are powerful because they control how traffic is identified. They are also where small syntax or routing mistakes can create symptoms that look unrelated.
- Validate YAML before reloading the profile.
- Place specific rules above broad fallback rules.
- Check whether DNS mode changes the domain or IP seen by rules.
- Disable TUN temporarily when isolating a full network outage.
Recommended handling
Make one configuration change at a time and reload the profile after each edit. If traffic stops entirely, revert to the last working profile before trying another DNS, rule or TUN change.
Practical notes
- Keep a backup of the last working YAML profile before editing advanced fields.
- Change one setting at a time so the result is attributable.
- Use logs and timestamps when asking for provider or community support.