Shelly problems and fixes
Shelly devices are Wi-Fi and Bluetooth relays, plugs, energy meters and sensors for home automation. The guides here cover problems you can check without touching the wiring: firmware updates, Wi-Fi and routers, cloud account and app, BLU devices and energy metering with home batteries. This site is independent and not affiliated with Shelly Group.
Every Shelly problem covered on this site, in one place. Each guide starts with the free checks in the app and web interface and refers wiring work to a qualified electrician.
Shelly problems
- ShellyShelly BLU device unresponsive after a failed update: rescue via bootloader modeIf a BLU device's firmware update aborts, the official documentation says it stays in bootloader mode. The update can be repeated from there: forget the device in your phone's Bluetooth settings, reinsert the battery, select it in the Shelly Debug app within about 40 seconds and start a slow OTA update. Shelly recommends an Android phone for this.Battery-powered BLU devices, e.g. BLU TRV, BLU Button, BLU H&T, BLU Door/Window, BLU Motion ·
- ShellyShelly: "Device belongs to another user" – check the device ID and fix it properlyThe Shelly Cloud assigns each device to exactly one account. A factory reset doesn't remove that. First read the device ID: if it's only 6 characters, Shelly support says to use the long ID (longifyid) or update the firmware. With 12 characters, the previous owner has to remove the device from their account; otherwise Shelly support helps with the device ID and proof of purchase.All Shelly devices with cloud connection (Gen1 to Gen4), common with second-hand devices ·
- ShellyShelly firmware update fails or is stuck at 99% (Gen3/Gen4): what helps and what doesn'tThe update aborts, reports an error or stays at 99%. First reboot and start the update from the local web interface instead of the app, check the Wi-Fi signal, briefly turn off Eco mode and update devices one at a time. Never cut power during an update. If that doesn't help, Shelly support is the right contact for Gen2+; according to the sources a factory reset does not fix it.Gen3 and Gen4 devices (e.g. Plug S Gen3, Plug M Gen3, Pro 3EM, 2PM Gen4); much of it also applies to Gen2/Plus ·
- ShellyShelly keeps going offline or won't connect to Wi-Fi (incl. FRITZ!Box): settings that actually helpShelly devices need a stable 2.4 GHz Wi-Fi: 20 MHz channel width, channel 1, 6 or 11, WPA2 (AES), no band steering and enough signal. On a FRITZ!Box that means: fix the channel, WPA2 instead of mandatory WPA3, check PMF and let devices talk to each other. Only then network reset and re-adding.Gen2/Plus, Gen3 and Gen4 (Wi-Fi devices); the principles also apply to Gen1 ·
- ShellyShelly Pro 3EM with Anker Solix (error 35) or Marstek Venus: check the connection and understand the "phase_sequence" warningError 35 "wrong meter connection" in the Anker app and a Marstek Venus that gets no readings from the Pro 3EM often have simple causes: unsupported meter model, Wi-Fi (guest network, weak signal in the distribution board), wrong UDP port or measurement direction. The Pro 3EM's "phase_sequence" warning, according to Shelly, means the phases are not connected in the order A–B–C; according to the forum it doesn't matter for metering itself and can be turned off. Rewiring only by a qualified electrician.Shelly Pro 3EM (also Shelly 3EM) as the meter for an Anker Solix Solarbank or Marstek Venus ·
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Official Shelly support
Device faulty or still under warranty? Contact official Shelly support. This site is independent and not affiliated with Shelly or Shelly Group. Shelly support (official)
All Shelly guides, newest first
5 guides on this site, newest first.
- ShellyShelly BLU device unresponsive after a failed update: rescue via bootloader modeIf a BLU device's firmware update aborts, the official documentation says it stays in bootloader mode. The update can be repeated from there: forget the device in your phone's Bluetooth settings, reinsert the battery, select it in the Shelly Debug app within about 40 seconds and start a slow OTA update. Shelly recommends an Android phone for this.Battery-powered BLU devices, e.g. BLU TRV, BLU Button, BLU H&T, BLU Door/Window, BLU Motion ·
- ShellyShelly: "Device belongs to another user" – check the device ID and fix it properlyThe Shelly Cloud assigns each device to exactly one account. A factory reset doesn't remove that. First read the device ID: if it's only 6 characters, Shelly support says to use the long ID (longifyid) or update the firmware. With 12 characters, the previous owner has to remove the device from their account; otherwise Shelly support helps with the device ID and proof of purchase.All Shelly devices with cloud connection (Gen1 to Gen4), common with second-hand devices ·
- ShellyShelly firmware update fails or is stuck at 99% (Gen3/Gen4): what helps and what doesn'tThe update aborts, reports an error or stays at 99%. First reboot and start the update from the local web interface instead of the app, check the Wi-Fi signal, briefly turn off Eco mode and update devices one at a time. Never cut power during an update. If that doesn't help, Shelly support is the right contact for Gen2+; according to the sources a factory reset does not fix it.Gen3 and Gen4 devices (e.g. Plug S Gen3, Plug M Gen3, Pro 3EM, 2PM Gen4); much of it also applies to Gen2/Plus ·
- ShellyShelly keeps going offline or won't connect to Wi-Fi (incl. FRITZ!Box): settings that actually helpShelly devices need a stable 2.4 GHz Wi-Fi: 20 MHz channel width, channel 1, 6 or 11, WPA2 (AES), no band steering and enough signal. On a FRITZ!Box that means: fix the channel, WPA2 instead of mandatory WPA3, check PMF and let devices talk to each other. Only then network reset and re-adding.Gen2/Plus, Gen3 and Gen4 (Wi-Fi devices); the principles also apply to Gen1 ·
- ShellyShelly Pro 3EM with Anker Solix (error 35) or Marstek Venus: check the connection and understand the "phase_sequence" warningError 35 "wrong meter connection" in the Anker app and a Marstek Venus that gets no readings from the Pro 3EM often have simple causes: unsupported meter model, Wi-Fi (guest network, weak signal in the distribution board), wrong UDP port or measurement direction. The Pro 3EM's "phase_sequence" warning, according to Shelly, means the phases are not connected in the order A–B–C; according to the forum it doesn't matter for metering itself and can be turned off. Rewiring only by a qualified electrician.Shelly Pro 3EM (also Shelly 3EM) as the meter for an Anker Solix Solarbank or Marstek Venus ·