On free Wi-Fi with captive portal, rethink caches responses before logging into the network1. This means that anything that makes a request before being able to log in doesn't work after logging into the captive portal, as it has the wrong information cached. Rethink itself reports to me that I'm offline when I'm connected to a captive portal. (I usually don't want to use the captive portal, so I don't log in, but my phone connects automatically to the bus network since I do use it in some places)
On free Wi-Fi with captive portal, rethink caches responses before logging into the network1. This means that anything that makes a request before being able to log in doesn't work after logging into the captive portal, as it has the wrong information cached. Rethink itself reports to me that I'm offline when I'm connected to a captive portal. (I usually don't want to use the captive portal, so I don't log in, but my phone connects automatically to the bus network since I do use it in some places)
Footnotes
I'm not clear if it's caching nxdomain, dropped replies, or mitm'd DNS responses, I haven't looked that far. I use DoH for system DNS, so I suspect it's timing out as it shouldn't really be accepting responses from the portal with the wrong/no certificate. ↩