My Nexus 7 has always had poor reception compared to our ipad. The kitchen was beyond its capabilities.Since placing these foil trays my speed has gone from 5 to 12 whatsits and I can browse in the kitchen.
I’ve even watched stuff on you tube in one go without buffering . Very happy.

I’ve just updated mine, sadly couldn’t get Infinity, but I got one of the new HomeHub 5’s. It’s rubbish! It can barely manage two bars in the next room, and nothing at all upstairs, whereas my old, white HomeHub 1, while painfully slow, would happily show three bars in the next room, and two upstairs in my bedroom. Not impressed, as it’s advertised as offering better coverage. 🙁

can you explain why that would work …

Smoke and mirrors.

How will Google be able to secretly collect information on you now?

Just google “wokfi”

The RF signal will reflect off the metallic surface. Your signal would be crap behind that as most of the signal is being pushed in one direction. Interesting that it works as well as it appears to from what you say as you will have a lot of multipath and it is just as likely, if not more so that you might get a poorer signal due a sub optimal antenna deployment.