You switch provider, a new router arrives, and the next day none of your Shelly devices answer from the phone. The physical switches still work, but remote control has gone. Nothing is broken: each device stored the name and password of the network it was set up on, and that network no longer exists.
How much work you have ahead comes down to one question: is the old router still switched on?
If you have not set up the new router yet
Give it the same SSID and the same password as the old one and you are done. The devices reconnect by themselves and you touch none of them.
It sounds too easy, but it is the difference between five minutes in the router’s admin panel and an afternoon opening back boxes. If you have devices buried behind a switch plate, it is frankly the only comfortable option.
If both routers are on at once
This is the window people waste. While the old network is still up you can migrate every device in one go; the moment you switch it off, it is one at a time.
With the SIT-IoT app, your phone on the old network and automatic configuration running, the devices in range are reprovisioned one after another onto the new SSID. It is the same procedure you use on a fresh installation, applied to one that already exists.
Two conditions that are not optional:
- DHCP on the new router only. With both handing out addresses you get IP conflicts, and a diagnosis considerably more confusing than the problem you started with.
- Set the static IP while you are reprovisioning. If the devices were on DHCP, this is the moment to take that dependency away so the next router change does not repeat the whole story.
If the old router is already gone
The manual method is left, and it always works. Hold the device’s button for about five seconds until the LED turns blue: it is broadcasting its own access point, named something like ShellyPro3EM-XXXXXX.
Connect the phone to that network — ignore the warning about there being no internet — open 192.168.33.1 in the browser, and enter the new SSID and password in the Wi-Fi settings. If the device’s network does not appear, cut its power for a few seconds before pressing again.
On devices that support it, configuring over Bluetooth avoids having to reach the button at all — which is exactly the problem when the unit sits behind a switch plate.
When it still will not connect: it is the router, not the Shelly
Most of the cases that survive all of the above have the same cause: modern routers ship with defaults these devices cannot work with.
- They only see 2.4 GHz. The radio is 802.11 b/g/n and the 5 GHz band does not exist as far as they are concerned. If the router publishes both bands under one name, the device may never find the one it needs. Separate them with different names, or turn 5 GHz off while you configure.
- WPA3-only does not work. They need WPA2 as a minimum. Leave it on WPA2 or on mixed mode.
- Automatic channel. Fix it to 1, 6 or 11 at 20 MHz. Those are the non-overlapping ones and they give noticeably steadier connections.
- Odd characters in the password. Before writing a device off, try a plain alphanumeric key to rule it out.
The LED tells you where to look. The one that misleads people most is yellow: it means the Wi-Fi is fine and the problem is the route out to the internet. Do not touch the device’s network settings there — check the router.
How to know which ones actually came back
This is the step missing from most guides. You reprovision fifteen devices, check three, and call the job done. A month later the one that was left out turns up.
In the console, the last seen column settles that at a glance: the ones that came back update, and whichever still shows the date of the router change is exactly the one you are missing. No walking the house, no relying on memory.
You will also see each device’s firmware version, which usually gives away the unit that has been off the network for a while.
The questions that always come up
Do I lose automations or history by changing network? No. Changing the Wi-Fi only touches the connection details. What does wipe everything is a factory reset, which is why it is the last resort: ten seconds on the button and your automations and calibrations go with it.
They connect but drop out constantly. Congested channel or marginal coverage. Fix the channel and the width. On large installations, some domestic routers simply struggle with dozens of clients on 2.4 GHz.
I have a mesh network. Restart the main node first, then the satellites. Some battery devices stay pinned to the access point they were configured on, to save power.
Do they work without internet? Yes, locally, through their web interface or over MQTT.
The order, in short
- Can you reuse the SSID and password on the new router? Do that and stop here.
- Is the old one still on? Reprovision in a batch from the app, with DHCP on the new router only.
- Check the new router has 2.4 GHz under its own name, WPA2, and a fixed channel.
- Whatever is left, in AP mode from 192.168.33.1.
- Check in the console which ones came back. Factory reset only if there is no alternative.
The app and the console work with Gen2, Gen3 and Gen4 devices, so the procedure covers a whole installation even when it mixes hardware from different years. The app is on Google Play: SIT-IoT Smart Installer Tool.