It will probably reflect some of the radiation. Wifi reception will be poorer behind the aluminium and possibly better in front.

A cheapskates version of a directional antenna.

I unironically do something similar to this. In my area, the only options are a dogshit local WISP, Starlink/other satellite, or (where possible) cellular.

I am one of the "lucky" people who are able to use cell for my internet, however whether it's the cell company having a craptastic network, software/hardware bugs on the my customer equipment, or a combination of both, there is only ONE cell tower I can connect to which yields a useful connection.

All other towers result in the equipment failing to connect to the tower, connecting but failing to get an internet connection, or only yielding download speeds 5Mbit of less.

I have found that by shoving sheet metal around my ISP's equipment, I can quite easily block off the non-functional towers and ensure they're never connected to. I don't think speeds are any better, but it does help with reliability.

Long live the Pringles cantenna

Keeps out the conspiracy-based posts and only lets facts through.

On the Effectiveness of Aluminium Foil Helmets: An Empirical Study

I did this back in 2010-13, to get better internet in my house! It was a video from a youtube, where he used cereal box with aluminum.

I have put my router in a 4 m parabol antenna, with this the signal has also improved somewhat, it only prevents me from using the sofa that is next to the router.

This can actually be beneficial if your router is right at the corner of your house. The foil acts as a reflector for some of the radiation that would've been wasted, and thus improves the signal quality within your house.

Directs the wifi.

Remember windsurfers? You put them on the single antenna of your old linsky router.

Not as effective as the anti-5G wire cages.

uh, is this real?

Remember Pringles antennas? Same energy.