Are you onVerizon? I think that's their icon for being on a fem-to-cell. Basically that's a device used to intercept a phone's signal in poor coverage areas, then transmit the data over a broadband connection. I'm guessing someone around you has one installed, but not sure how to avoid connecting to it.
Edit: Looks like if this is your situation, you're likely stuck and Verizon doesn't seem interested in fixing this issue to allow users to manually disconnect from an extended.
https://community.verizon.com/t5/Net...er/td-p/971510