DHCP for setting PIC Server inside some LAN. You may already be clear this.
To access PIC Server from outside of its LAN, it needs to be on a specific PORT and set the Router to pass packets destined for PIC from the internet based on that PORT number. On my router, I had to enter a static PIC address and specific PORT that allows packets to pass through. That doesn't change so from outside, IP and PORT # access to PIC stays the same. I'm not sure if some routers can add that routing based on the HOST NAME,instead of IP, that you may set in the 5100.

IPV6 will change this but thats still evolving as more devices handle the addressing protocols. I think.

The HTML pages parts stored locally would be because the PIC Server can only handle so much HTML, so that could make pages more functional and appealing while still getting timely data from PIC.

Don