onn 4K Pro: USB debugging keeps ADB on port 5555 over Ethernet, across reboots

On current Android, network ADB normally means Wireless debugging: a pairing code, a random port, and Android turns it off whenever the device isn't on Wi-Fi. Plug an Android TV box into Ethernet and network ADB goes away; reboot it and the port changes. That breaks Home Assistant's Android TV integration, ADBTuner and anything else that expects <box-ip>:5555. The usual fixes need root (persist.adb.tcp.port) or a helper app that turns Wireless debugging back on at every boot.

The onn 4K Pro's firmware sets service.adb.tcp.port to 5555 at every boot. That property only matters while the ADB daemon is running, and USB debugging keeps the daemon running whether or not the box is on Wi-Fi. With USB debugging on, the box listens on TCP 5555 from boot, on Ethernet as well as Wi-Fi. Nothing has to be plugged into the USB port.

Tested in three stages on one 4K Pro on October 17, 2026, then confirmed on a second:

• ›On Wi-Fi, no reboot: USB debugging on, Wireless debugging off. The ADB daemon kept running and port 5555 stayed open.
• ›Reboot on Wi-Fi: port 5555 open about 25 seconds after the reboot, with nothing else installed to help.
• ›Reboot on Ethernet only, Wi-Fi disconnected: port 5555 open on the Ethernet address about 33 seconds after the reboot.
• ›Second box, on Ethernet: back on 5555 about 34 seconds after a reboot.

$ adb shell getprop service.adb.tcp.port
5555
$ adb shell getprop persist.adb.tcp.port

$ adb shell settings get global adb_enabled
1
$ adb shell settings get global adb_wifi_enabled
0

1. 01Unlock Developer options: Settings → System → About, then press OK on Android TV OS build seven times.
2. 02Turn on Developer options → USB debugging. I set it over an existing ADB session with adb shell settings put global adb_enabled 1, which is the setting the toggle writes.
3. 03Check the firmware preset: adb shell getprop service.adb.tcp.port should print 5555.
4. 04Move the box to Ethernet, reboot it, then run adb connect <box-ip>:5555. Approve the computer once at the TV with Always allow from this computer.

This is plain, unencrypted ADB on port 5555. The only protection is the approval prompt, and an approved computer has full control of the box. Keep the box on a network you control, and firewall port 5555 to the machines that need it.

Android also revokes ADB approvals that go unused for seven days. If a computer only connects occasionally, adb shell settings put global adb_allowed_connection_time 0 stops the expiry, at the cost of approvals lasting until you revoke them.