Simple question but can be a complex answer. Basically it depends where your phone gets DNS from: if it’s using the ISP DNS (or some other public DNS server) it will resolve the public internet IP of your server and the data will route out to the ISP WAN before being routed back in.

On the other hand you can configure a split DNS system, so say you are using your modem/gateway as your DNS server and it forwards DNS queries up to your ISP (or other) DNS server - a common setup, 1. you can add in a static host entry for your local server. Eg ‘yourservice.yourserverdomain.com = 192.168.1.20 (your server’s LAN IP)’

Now when your phone is on the WiFi and it looks up your server’s address it gets the local IP and routes locally, which will be faster.

If you need more info, search for terms like ‘reverse proxy split DNS best practice’.

Yeah I use Linux for my servers and my HTPC, but I never really hibernate or sleep those so I had no idea if it might occur there too. It’s great to hear this is not likely to be an issue - thanks

The problem I have with this I put the PC to sleep overnight every night - and like clockwork, Windows wakes it back up sometime overnight to do… Something.

I’ve been diagnosing the issue for years - checking wake timers, switching hardware devices permissions to wake the system off. I might fix it for a few months and then a new Windows update comes along and it’s back to its usual routine of waking itself.

Looking forward to seeing if it persists with Linux when I move at the end of support period for Win10 later this year.