Unfortunately I have sort of the same problem. Broadcom 440x keeps reconnecting as soon as I start using webpositive. I remember that this issue existed already for years… This is my laptop I used to bring to BeGeistert. On current nightly (as of yesterday) I see that it’s even worse now: as soon as I connect a cable (it gets an IPV4 adress via DHCP, 100mbit, and I can briefly browse the web, intermittently) I run high risk of a system hang. I have to hard power down the laptop. Happens always after a second upto a minute. Also happens when using vision for example, or as soon as I start the update check app.
On older versions of Haiku (i.e. 2015, 2016) the reconnection thing occurs also, but no system freeze as far as I remember.