1. HAVE YOU TRIED TURNING IT OFF AND ON AGAIN?
There's a reason this is the adopted catchphrase of IT departments the world over (whether they like it or not). Some prefer to say 'power cycle', but it means the same thing. Smart devices, like any computers, might have minor bugs that, over time, fill their memory or cause them to freeze. If there is no switch, simply disconnect the power (and remove any battery), wait a few seconds, and reconnect.
2. CHECK THE POWER
It sounds obvious, but with things like smart bulbs that can be switched off at the wall as well as operated using an app it's well worth checking you (or someone else around the home) hasn't switched something off by mistake. Similarly check the batteries of both the product in question and any that it relies upon.
3. SOFTWARE UPDATES
Check that you have the latest version of any smart device's app installed on your phone, and the latest firmware installed on the device itself. If you don't, it's very likely that you'll be told to do this before calling back. Although many devices do update themselves regularly, you can usually find a 'Check for update' option in your app's Settings menu to make absolutely sure.
4. CHECK CONNECTIVITY (WI-Fl)
With wireless gadgets, you need to make sure they've actually connected to the Wi-Fi router or smart home network in question. If possible, try moving the device nearer the router and seeing if it works there.
5. CHECK CONNECTIVITY (MESH)
Most smart home networks are mesh networks, meaning they use each other as nodes to pass the message along. If you unplug a smart bulb in the middle of your house that was acting as a node for your back garden light, you might find that you can't now control that distant garden light from the hub even though it's got power.
6. CHECK CONNECTIVITY (INTERNET)
Working within your home network is one thing; having connection to the wider world is another. Check the lights on your router to see if it is connected to the internet. In some cases you'll also need to check the speed of the connection; use a web service like www.speedtest.net to see if you have the bandwidth to support a heavyusing device like a camera. Upload speeds are usually much slower than download, and each camera will eat up 1-2Mbps of the total.
It is also possible that the internet connection is fine but the systems needed at the other end - the manufacturer's servers - are temporarily unavailable. It is often the case that you still get a vague message like 'cannot connect'. Visit the manufacturer's website to check for any service notifications.
7. MY ROUTINES WON'T WORK
If Routines, Shortcuts or IFTTT applets that you have created stop working, check that your applet still has permission to use the accounts involved. If it uses a paid for service, like a subscription to a Microsoft email account, are your payments for that service up-to-date?
8. MY ASSISTANT CAN'T FIND A DEVICE
Check that the device is compatible with the voice assistant/smart speakers of your choice, or its platform (i.e. 'Works with Apple Homekit' is good news for Siri users). That means that you should be able to find the device on your network. You can use your Apple Home, Alexa or Google Assistant app to see the connected devices and check their names so that you know you're asking Alexa for the right device.
9. ASK THE INTERNET
Many manufacturers have their own community support forums, and still others exist in which you may well find people have encountered the problem you're experiencing and have shared the solution. You might have to scroll through a few pages of on line discussion, but many find this preferable to a phone call as they can refer back to the screen.
10. NOTE DOWN THE SPECIFIC MODEL/SERIAL NUMBERS
If, after all that, you're still going to take advantage of the manufacturer’s support - and there is no reason why you shouldn't, it is a service you have paid for - then try and have as much information about your product to hand to make the call I that bit easier, and keep a note pad ready.