Hi dude, how is your topology look like? Where is your fileserver? Maybe I can help.

Hey dude, What't your Online detection setting like? For Auto Mode, it will ping to the gateway of itself, which means if you have a device before the R480T+, and it will always show online.

Hey,dude. I think it can't support that function.

If you want to PING the router's WAN IP address, you have to check the Block Ping from WAN option on the page of firewalls.

Hi dude, if I've got it right, the R480T+ only have up to 4 WAN ports.

I can only tell you for V4 it is 64. V2 is too old, sorry.