Has this worked before or are you setting it up now? Was it used on S1 or S2 before?
To set up any Sonos device you need an internet connection. So you could either set up the Playbar at another location or use two phones to connect the Playbar to the internet, whereby one phone would provide the connection and the other would be used for the Sonos app?
For 1., do you know that your TV has the optical output turned on? Also, do you know what type of signal is being sent by the TV, and by implication, the devices feeding the TV set?
Hmm, having read your post several times now, you won’t get 1. Resolved until you get 2. (The setup of the device) complete. And, as @106rallye states, in order to set up the device, you must have an Internet connection. Once it’s set up, that Internet connection can potentially go away.
Has this worked before or are you setting it up now? Was it used on S1 or S2 before?
To set up any Sonos device you need an internet connection. So you could either set up the Playbar at another location or use two phones to connect the Playbar to the internet, whereby one phone would provide the connection and the other would be used for the Sonos app?
As far as I know, this hasn’t worked before. There’s always sound from the TV so I guess other users thought the soundbar was working 
But I’m 100% sure it’s not.
I’m not too sure how to use 2 phones to create a network in the same way I could with a typical router. I guess the easier way would be to take down the (wall-mounted) Sonos Playbar and bring it somewhere else with an internet connection.
You let one phone provide the WiFi, install the Sonos app on the other phone and set up the Playbar like you would on normal WiFi.
See https://support.sonos.com/article/set-up-your-sonos-playbar
For 1., do you know that your TV has the optical output turned on? Also, do you know what type of signal is being sent by the TV, and by implication, the devices feeding the TV set?
Hi. Yes I confirmed that the optical output is working, by unplugging from the Sonos and plugging in to another (brand) set of speakers. I was using the TV’s digital-tv tuner directly to watch free-to-air TV channels.
You let one phone provide the WiFi, install the Sonos app on the other phone and set up the Playbar like you would on normal WiFi.
See https://support.sonos.com/article/set-up-your-sonos-playbar
I tried this 1. switch off the router; 2. turn on Mobile Hotspot on 1 phone; 3. connect 2nd phone (with Sonos S1 app) to the WiFi] but couldn’t detect the Sonos.
So in the end I unplugged everything and carried the Sonos to another location with a router and internet access.
Managed to set up the Sonos in this way. Hope I won’t need to do this ever again
