Check whether your Wi-Fi network allows phone-to-phone transfers
If Files To Other Devices does not find the other phone, check the network before trying a large transfer. The application must be open on both devices, and both must be connected to the same Wi-Fi network.
Step 1: compare the Wi-Fi connection
Open Android's Wi-Fi settings on each phone and confirm that both are using the same intended network. A main network and a similarly named guest network may be separated even when they use the same router.
Step 2: check device isolation
Some routers have options called client isolation, AP isolation or guest isolation. When enabled, they may prevent connected devices from discovering or talking to each other. On a network you administer, review these settings and any firewall rules relevant to local device-to-device communication. Do not weaken security on a shared network you do not control.
Step 3: run a small test
- Open the app on both phones and follow any permission prompts.
- Find and connect to the receiving device.
- Copy a single small file and verify it on the receiving phone.
If it works on your trusted home network but not on a hotel, school or public Wi-Fi network, the network's restrictions may explain the difference. Ask the administrator about permitted device-to-device communication rather than assuming that an undocumented port should be opened.