Has this option been moved/removed as I have a work wireless connection that keep disconnecting with a message about poor internet performance and I'd like to keep that wifi connection even if something is causing it to flag as slow. Connection is always "good" with link speed 150Mbps. Personal wifi router connections have been fine - just no options for any control over work routers.
if you have 2 or more connection in the same range and you want to keep one as automatic connect, just click on the one that you don't want to connect and select "Forget".
Keep in mind, network protocols make 2 devices to drop connection when speed or connection is not good, that has nothing to do with you allowing anything or not, or making the connection to stay on at all times, it's not up to you or me, but the protocols that are applied.
I think the setting you are looking for is under Settings> Wi-Fi > Advanced > Check for Internet service.
When I have that disabled I don't get disconnected when I have a Wi-Fi connection that is flagged as slow.
Were the suggestions provided by Dj_Damjano and EvanL helpful at all? Please fee free to let me know if you're still in need of assistance.
Sprint Social Care Team