When NAT isn't working, here's how to diagnose:
Check translations:
show ip nat translations
If empty, traffic isn't matching NAT rules.
Verify interface directions:
- Is "ip nat inside" on LAN interface?
- Is "ip nat outside" on WAN interface?
Check access list:
show access-list 1
Common problems:
- Asymmetric routing
- Overlapping address spaces
- Exhausted NAT pool
- Timeout too short
Clear translations if needed:
clear ip nat translation *
This disconnects all users temporarily.