2 gang 2 way switch help needed

[rightnoob]

The sticky has me a little confused mainly down to the wire colours.
Whilst plastering the downstairs hall, unscrew the light fitting to ease the job it seems the fitting was not connect correctly as all but 1 wire came out of the fitting.
My wiring consists of 2 black wires and 3 red wires.
The fitting has 2 common 2 L1 ans 2 L2

I have reconnected with the following results:

Left side top 1 common Red wire bottom L1 Black L2 Black
Right side top 1 common Red wire bottom L1 empty L2 Red
The switch operates upstairs landing and the downstairs hall and always 1 light is on I can't turn both off or have both on lol
help me please guys

 

[ban-all-sheds]

The fitting has 2 common 2 L1 ans 2 L2

It's usual to call that a "switch"....

Anyway, go and buy a multimeter.

In the meantime, can you see which red/black pairs are in the same cables?

Do you have just a 1-gang switch upstairs, or is that a 2-gang 2-way as well?

No earths???

 

[rightnoob]

1 gang switch upstairs, can't really tell which wires are paired up, the back box is broken so I will remove that tomorrow for a better look.