It was my image. I recreatred it from an other one and I thought it was wrong but in fact the numbers although they are swapped are correct in both the before and after images. They are switched on purpose so the diagram is easier to read! With regards to the biggest hassle I had - which was how to figure out which traveler was which - there a a youtube video in that savme facebook link that I supplied, where an electrician has a very clever way to quickly determine which traveler is which. Label them all and you should be set!
@bodaw I had the same issue and just decided to go with old fashioned incandescents so that I would not have to worry about using a bypass. The Shelly 1L is discontinued now (so I bought spares off ebay) and I have found it impossible to find any Shelly by passes for sal that are for 120V.
I spoke with the founder of shelly and asked him what would replace the 1L and he said in the fall of 2023 they are coming out with something. I asked for some hints about what it would look like etc - and there was no reply.
It is not a neutral. Those were my diagrams and I had no neutral available, that is why I had to use a Shelly 1L
Hello,
Re the original wiring solution, are you able to help me out if I was putting the Shelly 1L with the second switch?
That is exactly where I put my Shelly 1L and this is how to do it.
Thank you so much for the detail, my challenge is that I need to put the Shelly on the other switch, I do have access to a live feed however.
I did get this and will try and understand it, from a diagram side of things.
with a 1L, use 1-1 to connect the left switch to SW1 and then connect one terminal on the right switch to SW2. Live is connected to both switches and L (I would probably use 2-2 for this to ensure it’s all on the same breaker). Then O goes to the fixture.
I did see the diagram you posted and thought it was the answer but realised I am working at the second switch not the other that you connected too.
The other switch for me is in brick and can’t fit the Shelly and the coverage would be crap anyway.
You can put it behind either switch, that doesn’t matter
If you have no neutral at the switch then this would not work
I do have a neutral there but was thinking the ‘O’ would go the the bulb and remove it from the common on the switch.
I also have a live I can bring into the Shelly.
Must admit I am struggling 
Yes I believe that is the way. Also be sure to determine which of the wires in each switrch box is a ‘traveler’ that is, which two are coming from the other switch. You do that by watching the youtube video in the link I supplied. Just think your way through it and try to even draw a diagram yourself on how to do it. After much thought if you are still confused or not sure 100% about the way you think it should be done, enter a ticket with shelly and attach your diagram, they will tell you if you are doing it right or not (and if the diagram is right). (Once I was not sure of what people were telling me on a forum, and I reached out to Shelly with my diagram and they corrected me. To be honest, if you are doing something with electricity in your home and you are not sure and still do not want to hire a licensed electrician to do it for you (and he/she might get it wrong too!), then reach out to Shelly - they will answer (it might take a little while because they are backed up) - and they will be absolutely certain to make sure they give you the correct answer - 
I did get this from Shelly:
Use 1-1 to connect the left switch to SW1 and then connect one terminal on the right switch to SW2. Live is connected to both switches and L (I would probably use 2-2 for this to ensure it’s all on the same breaker). Then O goes to the fixture.
Now trying to decipher it.
Always go with what they said. When deciphering it write a diagram up and attach it to a reply to them and ask them if it is correct
Does anyone have a wiring diagram for the Shelly Plus 1, as it seems that the 1L is discontinued.
I have three unused Shelly 1L. I pulled them out of the wall and replaced with a Shelly model that does power monitoring.
I’m thinking about listing these on ebay but I’m not sure they have any value.
I think I have Tasmota on them. I don’t know how to revert them back to the original firmware. Ugh, I guess they will just sit in a draw.
This got me so close to figuring my case out! I have a Shelly 2 dimmer I’m trying to install into my two-way on/off switches. With this method I managed to get the 2nd switch to perform correctly (on/off) while the Shelly does its job too (full control). But the 1st switch is completely irresponsive. Is this expected because I’m using a wrong Shelly model?