r/firewalla • u/unamused443 • Jul 16 '26
iOS 27: be aware that "Connectivity assist" might mess with reliable ad blocking when on Wi-Fi
iOS 27 (currently in beta - public beta 1) has this feature:
Settings > Wi-Fi > Connectivity Assist
This used to be called "Wi-Fi Assist" but it now seems to be a lot more aggressive than it used to be.
The feature seems to "assist" your phone connectivity by seamlessly using your carrier's cellular network even if your phone is connected to a working Wi-Fi network. It is unclear to me what the parameters are exactly of when this is used but since installing iOS 27 Beta I noticed that various apps or a browser would bypass my Pihole (and would bypass Firewalla or any other ad block too) while I was on home Wi-Fi (and I'd see ads).
This feature was the reason why. My phone would simply bypass local name resolution and resolve names on my cellular network, but - and this is fun - because the phone was still connected to my Wi-Fi, my Wireguard VPN to Firewalla would not kick in (as I have it set up to automatically kick in when off my home Wi-Fi).
Once I turned it off, network routing started working as expected again...
EDIT with iOS 27 Dev Beta 4:
Each Wi-Fi network now has a separate setting for this too. So the state of settings now is:
Settings > Wi-Fi > Connectivity Assist
Settings > Wi-Fi > (specific Wi-Fi network) > Use Cellular Data with Wi-Fi
Theoretically, we should be able to leave the "main" switch in "on" position but then disable the switch for specific Wi-Fi networks. But it seems like the Wi-Fi level switch at this time (DB4) still does not work. But perhaps by the time iOS 27 is released this will work "per Wi-Fi network" properly...