chantelw2489 :
This started happening to me a day after updating all my apps something is affecting this, i figured this out today while underground and my wifi goes in and out as soon as I turned it off my bluetooth headphones never disconnected again. I wish I knew which update is making this happen I updated all my Google and Samsung apps. This started yesterday after the update on Wednesday.
Same issue, HTC U11. The problem is specific to bluetooth audio; if I get in my car and let the phone connect to it, the audio from the phone switches from the car speakers to the phone speakers as soon as I drive out of wifi range, unless I turn off wifi before I start the car. However, the phone is still BT-connected to the car; I can navigate the phone book and make calls, but the audio comes out of the phone speaker. Turning off the bluetooth and turning it back on fixes the audio issue.
Also, if I don't turn the wifi off, the bluetooth audio will disconnect again when I get to work and my phone makes a wifi connection to the wifi at work. What it appears to boil down to is: any time the phone connects or disconnects from a wifi network, the bluetooth audio changes source. The only fix I know is turning bluetooth off and back on, plus keeping wifi turned off if I'm near any networks and want to hear music.