Shelly Plug S seems to trip power outlet?

Something we've had several times now. When switching on a Shelly plug with the little button, it trips the power outlet. And hence, that takes down all stuff on that circuit. Happened twice today, with different Shelly plugs / electrical circuits. So I wonder if there's a problem manually switching the Shelly plug? The plugs in question only host a pc, so no big load. Any ideas?

The outlets are rated 16 amps. The pc's are set to power on when the power cord is plugged in, i.e. as soon as power is applied.

The power supply of the pc's is rated 400 watts, so at a maximum, it will draw about 1,7 amps.

Before we had the Shelly plugs, the pc's where set to automatically power on at a given time. So they where in stand-by all the time. Since not everybody starts working the same time every day, some pc's are switched on, but not used. Just idling away, which is a bit of a shame. So that's why we decided to introduce the Shelly plugs to let everyone switch on their pc when needed. This means the machines are no longer in stand-by mode and I guess they initially take a little bit more power when switched on. Thing is - the fuse trips only when the Shelly is manually switched on. I.e. with the button on the Shelly plug. To complicate it, the fuse isn't always tripped when using the button. But when it IS tripped, it's when the button is used.