Hi! This was an important day as I tried
all the "route" that cable will have to do in those conduits and I made it almost smoothly!!!
I'm confident I will be able to do it.
1G network (where are those?).
You are right
@etorix , those copper cables are in other conduits, with TV antenna and those conduits are totally full, It would be impossible to use them (they're not visible in pic). Luckily I have these other conduits that were never used and totally empty!
Now I show you and I try to explain what I did today to test if what we are trying to achieve is possible:
The black "cable" you see It's the cable probe, and I used it to run the wire in the walls and also to take measure!
I attatched to the cable probe the random LC cable I bought LC-LC:

I cut it in half, so i got "4" cables, and the "head" of this cable was splitted in two, so i got 4 LC connectors one after one as you can see in pic, as if they were 4 cables at the same time ( I will need cable with the head that can be "split" in two" like this).
I also was able using scotch tape on the cable probe, to take measure, of the wire that I'll need through walls and also measure of the short route the cable will do in the two room do get down from the wall to the computers.
I will need two cables of 33 meters about each.
I'm confident this is possible, and we will be able to achieve this!
I can't wait for the next month to get FTTH as soon as possible, and order all the cables and the rest I'll need.
x3 SFP Cards have also been shipped!
Thank you as always!
Andyapple