Did you turn off masquerading on the WAN zone? And did you allow forwarding from WAN > LAN? Those are both important.
If those don't fix the issues, let's see your configuration...
Please copy the output of the following commands and post it here using the "Preformatted text </> " button:
Remember to redact passwords, MAC addresses and any public IP addresses you may have:
cat /etc/config/network
cat /etc/config/firewall