A bit of an update since leaving both machines overnight.
I can now add a remote device on Machine A or B and they are both showing on each others add screen "You can also select one of these nearby devices:” but they are both showing as disconnected. I have added folders on each but nothing happens, just always disconnected?
I think the issue is that when adding a folder on Machine A it never comes up on Machine B (prompts to add folder)
I have no idea, but I suggest you do a simple netcat test verifying that you can listen on one side on port 22000 and send to the listening port from the other machine. If that does not work, then it’s a problem beyond syncthing.
Also, if I add machine B from Machine A do I need to do the same on Machine B or should it come up automatically (Prompt) on Machine B? just seems strange that both Machine A & B can add/see each other are there but then be permanently disconnected?
If they could connect, the prompt would come up, but in general terms, A needs to add B and B needs to add A for them to have mutual trust.
Regarding netcat, you got the listening side setup, now you should send some message from the other machine to this one. Usually it’s done something like this: echo test | nc [ip of other side] [port other side is listening on], yet the arguments/order can vary between distributions, so best you read the manual by running man nc.