At some point towards the end of last year (2019), Wi-Fi started frequently dropping off and then automatically reconnecting on my MacBook Air 2018.
At least two things happened around that time, that could have triggered the issue, but I do not remember when they happened and in which order, and whether it even was before or after the issue started occurring:
- macOS update from Mojave to Catalina,
- light drop of the laptop, which didn't seem to have affected anything else.
Things I gradually noticed during the investigation:
- My connection is 50Mbs down / 4Mbs up, and it seems to be easier to reproduce when uploading data rather than downloading. Consistently able to reproduce when on a Skype call.
- Eventually able to reproduce when downloading a file from test FTP server, even with very low speed limit set on client side.
- Able to reproduce at home with 802.11n (2.4 GHz) network.
- Unable to reproduce at home with wired connection.
- Unable to reproduce at home with any other device using wireless connection, including another mac laptop (MacBook Pro 2018), Android phone (Motorola moto G6), and Windows laptop (Asus Y50-70).
- Unable to reproduce in the office, where network is mixed 802.11ac (5 GHz) / 802.11n (2.4 GHz).
- When watching
/var/log/wifi.logaround the disconnect events, the following line caught my attention for some reason:
<kernel> AppleBCMWLANCore::getSSIDData(): Get failure: APPLE80211_IOC_SSID: -528342013
Various tweaks I tried, none of which helped: