3 Gang 2 Way Light Switch Help

[Floppy1234]

Hello, wonder if anyone can help please.
I have changed the gace plates on a 3 way light switch with 1 light for hallway.
I have put 3 red wires into COMS.
3 black into L2
1 x Grey cable to link downstairs 2 way to L2.

The lights for 1 way work fine in both sets of switches.
The light for the 3 rd on the right as you look at the photos is for the hallway light which works fine upstairs but will not operate as a 2 way downstairs.
Does not come on or off when downstairs.

Turns off and off upstairs.
The light worked fine before I messed with it and I hvnt got any before photos of how it was wired before.
Just wondering if anyone can see why the right side wiring will not work bar upstairs.
I have tried lots of different ways it seems but I have never got the downstairs 2 way to work.
Thank you.

 

[ericmark]

Sorry, wire colours mean nothing, in theroy all should be red or today brown, but makes it easier if we have more colours, so common to find red/black or red/yellow/blue, or new colours brown/blue, or brown/blue/grey but these colours do not tell you what the wires do.

There are two main methods to wire two way lights. We were shown this at school,

however in practice that method means a joint in the switch,

so we tend instead to use this method

so the joints do not need a connector block, you will note the two coms connect together but not to anything else, so start point is look at colour of the wire in com at other switch. Swapping L1 and L2 only changes if up or down to switch on, it will work either way. What is important is com wire.

 

[Taylortwocities]

Are any of the above photos of the wiring BEFORE you did stuff?