TP-Link Smart Plug

I have a TP-Link Smart Plug which I use via Amazon Echo, it has an 8 plug point gang plugged into it but over the past couple of weeks on three occasions, it has become stuck in the on position (I’ve had to reset it completely). Telling Alexa to switch (plug) off does not work, the Alexa app will not work and the TP-Link app shows the plug to be off even though the power is still flowing through it. The smart plug has great a wi-fi signal (only 5 feet away from the wi-fi node). Has anybody had this problem or got any ideas?

I set some of these plugs up for someone recently and I had some trouble getting them to connect which turned out to be a Wi-Fi issue. I think I read somewhere on the plugs they only support 2.4Ghz - could you separate your Wi-Fi into a 5GHz and 2.4GHz network and try again?

Is that possible with mesh?

I have another one which is working perfectly.