[flanbiscuit]

> This is my concern. I use my old pixel (3a) as an always-on Syncthing node but worry about the security implications.

Interesting, I've never thought of using an Android phone as a Syncthing node.

Is there a way for an Android phone to connect to Wifi, but not the internet?

I use Syncthing with local discovery only, which only needs the devices to be on the same Wifi network. Not having internet access and also not having a SIM card to get calls/sms/mms message should greatly reduce the risk of attack to the point where I wouldn't feel worried about it.

[Jaruzel]

> Is there a way for an Android phone to connect to Wifi, but not the internet?

If you can manually set the IP address on it instead of letting the WiFi AP give it one, then you can just leave out the default gateway entry - The device will then have no idea how to route network data outside of your local LAN.

Alternatively, set up a different WiFi SSID that gives out IP addresses, but again without a default gateway address, and have your device(s) connect to that instead.

Or finally, if your router supports it, set a rule to block your device(s) (via it's MAC address) from accessing the internet.

[flanbiscuit]

all good ideas, thank you!

I think the first option might be the easiest because it doesn't involve having to change anything on the router.

It does seem possible on Android to set a static IP and remove the Gateway (or maybe set it to 127.0.0.1 if I can't leave it blank?)

https://service.uoregon.edu/TDClient/2030/Portal/KB/ArticleD...