Насколько сильный должен быть сигнал, чтобы проникнуть через 30 этажей?

If you're able to get an antenna out the windows or balconies of the apartments so that the 2 antennas can see each other, then you might have a chance... and it seems that using 2 routers might be better than just using one router and one wifi adapter (most adapters don't have as long a transmitting range or as sensitive receivers.

A modified antenna, with a longer range or directional, like this Wi-Fi Cantenna (2.4GHz): How-to Make a Long-range Wi-Fi Antenna might stand a better chance too, but I wouldn't bet money on it.

If your available router(s) don't have removable antennas, you could try opening them up, finding the antenna wires or solder points and attaching an extension yourself. There are plenty of guides on that around the web, a search would be fruitful.

You'd probably have a much more reliable connection by just dropping an ethernet wire out the top window and pulling it in the bottom window, at least until the building manager complained or some neighbour decided to cut it out of the way.

Your only chance is if you can place two routers which can "see" each other without any object between them, that case just look for two routers with 150 m range and that will work (and probably they will be outdoor, so that's also a criteria).

As I write this it's the only chance, you won't find a router sending signals through 37 layers of ceiling.

An ordinary concrete wall attenuates signal by 10-15 dB. So you have in total at least 30*10 dB = 300 dB of attenuation. For signal level over 30 floors to be in the order of magnitude like you have now sitting near the access point, you have to add this much gain. You have to add is both for upstairs and downstairs signal, you want bidirectional communication.

This was very rough calculation. I completely ignored the fact the concrete in floor plates have a strong reinforcement (metallic grid) inside, which could interfere with signal, attenuating it further and adding reflections and noise.

Good luck finding equipment which could work in such conditions.

Copper ethernet through exterior wall is not your choice. Ethernet link length should be less than 100 meters (you have 130). It still might work (though not very good) until first thunderstorm, when it will work as antenna for the lightning.

The optical ethernet will definitely work, it is the solution which is used for such situation in enterprise. Do this if you can afford, you can easily get 1 Gbit/s of link, the one problem left is physical protection of a cable (from neighbours who could break cable with a knife).

Cheap way to do this is to have point-to-point wifi outside of the building If both rooms have windows in same wall, you could install antennas on carrier bars in direct sight of each other. This way you could get working wifi bridge. We still have complexity: a building wall parallel to the axis of signal, and that wall is very close to axis, likely crossing the first Fresnel zone of the signal. (For the first zone to be free of obstacles, you will need to use quite a long carrier bars, which is inconvenient.) Still, it will not break the whole zone, only half of it, so I believe it will work.

I have used Mikrotik SXT Lite for building such bridge, it perfectly works for 200 meters of link, but I didn't had such obstacles.