Networks

Yes, you can do it without physical access, but you will the “password” details to connect as a wifi client.

The “extender” then connects as a standard wifi client, and passes the network traffic to your computer using a secondary path (eg fixed, wifi, microwave, Ethernet over power, laser modulation etc).

Commercial extenders using ethernet over power between pairs are quite common (one near enough to the modem, the other near enough to the other end, and sharing a common (enough) power circuit), as are ones that provide wifi for the secondary channel (situated within the overlapping receive range of both ends).

There have been reports of passive extenders working but they appear to be hoaxes. It would technically be possible to have a a repeater that was actually just a broadband amplifier that didn’t decode the signal, but I would expect that to be rather problematic as you would also be amplifying the noise as well, and possibly require two pairs one for amplifying the signals going to and one for amplifying the signals coming from the modem / wifi access point. (Amateur radio repeaters are generally only one way at a time)

Yes you can but like the other guy said if you dont have a proper signal it would not really do anything.

Yeah I have noticed that there is wifi extender already on the network. (not mine) it's connection isn't any better. I was just hoping that if I got a boost in my apartment it might help.