My house came with a built-in microwave/convection oven combo.
It had a Wi-Fi symbol on it and I'm like no fucking way I'm hooking this up to the internet. I manually set the clock and walked away.
The next day was a minute off, The day after that another minute off. I set the clock again in case there was a drift detection
Nope. There's also no way to make the clock not come up.
And that's how my microwave got its own isolation VLAN.