@userYwgI7uwPMj Thank you for this information! This Community works largely with US based devices so it's hard for us to speak on exactly what may or may not be happening to your specific device. You are welcome to see if the Community can assist, but as many may not have the same device as you it might also be worth reaching out to your region specifically for more in depth assistance! You can do so by using this link: http://www.samsung.com/visitcountry Thanks!
I'm having the same problem. Been having it since I got the S9+. Been waiting to see this issue come up on a forum and I finally found this place! I'm from New Zealand and my carrier is Vodafone NZ. Anyway my auto connect doesn't work for bluetooth devices such as my car radio S6 edge and S7 and S5 did not have this issue!. I've reported this to Samsung NZ and no response has come from them. I'm extremely disappointed and should not be getting this bull from a flagship phone. This is unbelievable and disgusting.
I recently upgraded to an S10+ and ran into this issue with my 2019 Ford Edge. I narrowed down the problem to recently using Bixby Routines. I deleted the Bluetooth auto connect routine and that didn't fix the problem. Since you cannot uninstall Bixby Routines I just deleted all the routines that I created and thent went into the setting to turn off Bixby. That fixed the problem and the Bixby Routine app is gone.
I have the 2018 model of the Galaxy S9 Plus. After a recent Android software update, my 2014 Nissan Rogue stopped connecting automatically via Bluetooth. The fix above worked and the Nissan/Samsung now connect automatically.