Warpinator does not need an internet connection to transfer files between devices on a working local network. Your broadband can be down while the router still connects your laptop and phone. What matters is whether those devices can reach one another, not whether a website opens.
A phone hotspot can provide that local connection too, but its behaviour depends on the phone. Some models let the hotspot stay on with mobile data disabled; others do not. Treat it as an option to check on your own equipment, rather than a promise that every Android phone works offline.
Wi-Fi connected, internet unavailable: what actually changed?
The Wi-Fi connection joins your device to the router. The router’s internet connection is a separate part of the setup. Losing broadband does not necessarily stop traffic between two devices inside the house.
Think of sending a photo from the phone on your desk to the PC beside it. If both applications are already installed and can communicate locally, Warpinator does not need to upload that photo to a cloud account before the PC receives it. Installing an app, downloading an update, or fetching a file that exists only in cloud storage is a different task and may still need internet access.
The Linux Mint project describes Warpinator as a local-network file-sharing application. Windows and Android use separately maintained compatible clients. If you have not set those up yet, start with our Windows–Android walkthrough.
Which setups can work?
| Your setup | What to expect |
|---|---|
| Both devices on home Wi-Fi; broadband is down | A local transfer can still work while the router and local network remain available. |
| PC on Ethernet, phone on the same router’s Wi-Fi | It can work if the router permits traffic between wired and wireless clients. |
| Phone hotspot, PC connected to it | Worth checking. Hotspot support, discovery and mobile-data requirements vary by phone. |
| Phone uses mobile data; PC is on home Wi-Fi | They are not automatically on the same local network. Nearby placement alone does not connect them. |
| Both devices on hotel or guest Wi-Fi | Internet browsing may work while local transfers are blocked by client isolation. |
Try the router you already have first
If broadband has failed, leave the router powered on. Check that both devices remain attached to the intended local network. Open the two clients, compare their group codes privately, then send a small file stored on the sending device.
Use a file you can already open locally. A thumbnail in a cloud-photo app is a poor test if the full photo has not been downloaded. Check the received copy before moving on to a large folder. There is no benefit in changing firewall rules just because the internet indicator says “offline.”
Using an Android hotspot instead
A hotspot is useful when there is no router available, or when you want to compare a troublesome router with a simpler connection. The Android maintainer explicitly suggests a hotspot as a connection troubleshooting test.
- Make sure the file and both applications are available locally before changing networks.
- Open the phone’s hotspot settings. Set a password and keep the connection private.
- Connect the PC to that hotspot. Confirm it did not reconnect to a different saved Wi-Fi network.
- Reopen both Warpinator clients after the network change, then check for the peer and try one small file.
- If avoiding mobile data is essential, check whether the phone lets its hotspot remain active with mobile data off. If it does not, use a working local router instead.
The exact hotspot menu varies by manufacturer. Google’s Android tethering guide explains the general feature; your phone’s own instructions take precedence for its controls.
Will a hotspot transfer use my mobile-data allowance?
A local Warpinator transfer and internet tethering are different traffic. However, a PC connected to a phone’s hotspot may also download updates, sync cloud folders or load websites through the phone. Those activities can use mobile data even while the file you intended to send stays on the local connection.
That is why “the file is local” is not enough to promise zero cellular usage for the whole session. Where your phone allows it, disabling mobile data while keeping the hotspot running removes that uncertainty. Do not rely on an app’s transfer counter as a measurement of every process running on the PC.
If the devices still cannot see each other
First check whether both clients are using the new network. A PC can retain several adapters, and the app may still show an address from a VPN or another connection. Do not keep changing group codes and network settings together; you lose track of which change mattered.
If no peer appears, follow the device-discovery guide. If the peer appears but stays on connecting, use the connection-stage checks. Opening internet-facing router ports is not a fix for either local problem.
For an offline setup you plan to use regularly, test both directions while the internet is unavailable and keep a note of the client versions. A working home-router setup does not establish that a different phone’s hotspot will behave the same way.