sub gen 3

No error messages, when it is connected i get the message that it is installed but if it is not visible it should be un and replugged ….and then the whole circus starts again 

Restart your network. Router first, then everything else.

The dealer rep will come again ( for the 3 rd time ) tomorrow… the sonos help desk only works from monday to Friday during office hours…..

and the sonos rep seems to be on holiday….

what kind of a company is this?

Have you got the Era 100’s set up as surrounds, or as a second room?

If you go to Settings (the gear wheel at bottom right of the screen in the app), then System, you should see your room listed. It should say something like Lounge (or whatever room name you’ve used) and then (LS+RS+Sub)   If it doesn’t say that, what does it say?

Are you sure you added the Sub to existing system rather than new system?

Same room arc ls and rs are there but sub not connected, can not find the sub is the message 

In that case it’s quite likely not setup on your system. Have you factory reset the Sub and got it to show a flashing green status LED as mentioned in this support link?…

https://support.sonos.com/en-us/article/reset-your-sonos-product

If so, with its LED still flashing green, first fully close/re-open the mobile Sonos controller App and then goto ‘Settings/System/Add Product’ - and follow the instructions to get the Sub setup and added to the Arc Room and then see if it works whilst playing any music/sonos radio station etc.