Yes, unrestricted NAT is desirable. You might need to reconfigure the router. You might find useful info in these posts:
- Road from restricted to unrestircted! - #10 by SirNeo
- Snowflake standalone proxy in Docker: How to make NAT unrestricted? - #2 by WofWca
- Firewall needs/settings for running standalone Snowflake proxy - #2 by meskio
- Snowflake standalone proxy: Port range considerations
- [tor-relays] snowflake incoming UDP ports - #2 by meskio