Might be everything of all, noise of powerlines, appliances connected to it (most shitty stuff sellers getting to Lebanon has no certifications), even just shitty triac water heater can make power line noisy as hell.
Interference is terrible thing.
Once wifi rates in apartment was dropped due crappy CFL lamps owner installed.
Another example, critical site in one of exUSSR countries, we had to sweep one city block to find old guy with malfunctioning TV that was causing interference to huge satellite dish 8km away.
Did you try following things:
1)Put modem in box with small UPS (maybe DC ups, if u will find it)
2)Get with laptop to telephone cables box, find yours
3)disconnect telephone wires going to apartment
4)connect to box, your telephone wires, check speed
5)just connect back wires to apartment, check speed
Interference is terrible thing.
Once wifi rates in apartment was dropped due crappy CFL lamps owner installed.
Another example, critical site in one of exUSSR countries, we had to sweep one city block to find old guy with malfunctioning TV that was causing interference to huge satellite dish 8km away.
Did you try following things:
1)Put modem in box with small UPS (maybe DC ups, if u will find it)
2)Get with laptop to telephone cables box, find yours
3)disconnect telephone wires going to apartment
4)connect to box, your telephone wires, check speed
5)just connect back wires to apartment, check speed