OK most likely that the WebUI etc only allowed from a local network.
When you can WebUI in then under
System Management / Host Access
then what is it set too
Seeing in the whole inbound chain in the fwmonitor so presuming you mean
pre-inspection i stage
post-inspection I stage
This would indicate that the traffic getting through the Security Policy, also any Address Spoofing
Hence why suspect that locked down under the Host Access
As can access from local network then process must be responding and be attempting on the correct port.