PMS running on Mac mini, media files on Synology NAS. Both wired to ASUS RT-AC58U router.
Internal access works fine, across multiple devices.
PMS settings -> Server -> Remote Access shows the green tick. Have tried manually setting to port 32400 and port forwarding to the mini on the router, alternatively tried without specifying port in PMS and removing port forwarding from the router.
Canyouseeme.org shows port as open.
In both cases, the server shows as offline as soon as I'm off WiFi (using iPhone to test this).
This is driving me up the wall, what else can I try to get this sorted?