The IOT network on the TP-Link Deco systems are not isolated and have full access to the rest of your network.

Those speeds are perfectly normal for your setup and using WiFi

Looks pretty normal to me

You do not value all replies or you wouldn’t be so rude with some of the replies you have given back.

If you WON’T ask the ISP to move the ONT, then CAT6 to the other location is going to be your best solution. If you don’t like this answer, then stop posting asking for them on Reddit.