How to make an external two-channel antenna-feeder system for Wi-Fi 2.4GHz?

Question

WiFi

Greetings, dear radio operators and signalmen!
Given: an office router (Mikrotik RB2011UiAS-2HnD-IN) has two non-removable physical antennas 4dBi @ 2.4GHz (two-channel Wi-Fi path). The distance between the antennas is about 100mm.
It is required to hide the router in an iron box with a bunch of other junk, raise the box higher and lock the iron door with a lock, but at the same time pull both antennas out, because the box is made of iron, the door without glass, everything is grounded. Indoor installation, precipitation, frost, lightning and birds are not expected.
Having disassembled the case of the device ( link), detect MMCX pigtails. Therefore, a system of a pair of meter MMCX / RP-SMA pigtails on an RG316 cable and two household omnidirectional Wi-Fi antennas with the appropriate connectors suggests itself. Antennas can be screwed directly onto the connectors on the external bracket, the attenuation in the feeder can be compensated by a slightly larger antenna gain. It seems that in theory everything grows together, but I have never done this myself before.
Questions:
1) Will it work? How about MIMO 2x1 or 2x2?
2) How far apart should the antennas be mounted? As was originally intended by Mikrotik (100mm) or at any distance from each other? Is it possible to spread them at all on different sides of an obstacle (an iron box 19", fixed on a reinforced concrete pole of a monolithic type 400x400mm)?
3) Is it possible to mount two microwave channels with RP-SMA connector braids on a single metal case? Or do the channel braids need to be isolated from each other?
4) Is it necessary to ground the braids (on the box) or, on the contrary, let them hang in the air (on a bracket isolated from the box)?
It is clear that this is a collective farm decision, but the budget, as usual ... But the farm described is sold anywhere and is cheap.
thanks in advance

Answer 1

From the answer above, it is not clear from which of these beliefs MIMO will not work. I don't see any problem for MIMO to work.
Here are some recommendations for you
1) position two antennas relative to each other perpendicularly at 90 degrees (thus preserving the polarization of the chains)
2) the distance between the antenna and the nearest parallel object (no matter what, it should not be less than half the wavelength) i.e. not less than 6 cm.
3) adjust the mikrotik setting where each connection gives an attenuation of 0.5 and see the attenuation on the conductor.