Play 5's(2nd Gen) re-setup for rears for 5.1 with the same Playbar+sub and the same router setup as originally in base setup mode

Play 5's(2nd gen) re-setup as surrounds for 5.1 Dolby Digital with all the original setup equipment and starting as instructed with LS(left surround) it never gets recognized to proceed to RS and complete. Let me explain this more clearly. I have been using this setup as a 5.1 system since 9/15/2018. About a week ago, I lost the LS(left surround) Play 5(2nd gen) speaker from the system. The Sonos Playbar+Sub in boost setup still work perfectly fine. I also have the same type of Playbar+Sub setup in my master bedroom, no rears in that room. When trying to re-setup the Play 5's as they were previously used as rears for 5.1, I always get an error message when starting AS STATED IN THE SONOS instructions with he LS(left surround). I re-boot the Play 5 and wait for the solid white light, which I get, press/release the join button, wait to proceed, and I always get the error message 'not recognized...' and it asks if I would like to try again and I do and it never works. No router or WiFi has been changed and the Playbar is hardwired in the Boost setup. I can go to WiFI but I prefer the hardwired version. This is even more important and difficult for me to solve since my skydive 'incident' way back in 12/2011 which resulted in my severe disability, mostly physically but I did have a TBI. If you want to see more about that just go to caringbridge.org and search for Sage, and you will see all the injuries and surgeries, I lost count at 40. The importance of solving this comes from the fact that I pretty spend all day long watching films(mostly) or listing to iTunes and I want the 5.1 back and better music sound. Anyway, trying to reach Sonos is not easy which I find unusual since I live only about 60 miles south of the main office in Santa Barbara.:?