TL;DR: The Wi-Fi was blocking my custom DNS settings, so I connected on my iPhone, viewed the DNS servers that DHCP configured automatically and set the manually.
Recently had the pleasure of fighting against hotel Wi-Fi. It’s a simple captive portal that only requires you to accept the TOS but could not connect to anything.
First clue: I tried to curl google and got the response curl: (6) Could not resolve host: google.com. From this I knew DNS was not resolving
Next, following instructions on Reddit, I booted into safe mode and was able to trigger the captive portal and access the internet. So I inferred there was something weird with my laptop’s configuration. I hadn’t remembered setting custom DNS but I looked and I had set 1.1.1.1.
Figuring the Wi-Fi was blocking my DNS requests, I thought about how to fix that and I also realized whatever DNS settings I happened to have on my iPhone must be the right ones. When I looked, the ip of the dns servers were 10.146.24.2 and 10.146.24.3. I also knew the IP of the router was 10.146.24.1 curious… I realized the router was blocking DNS and required I use one of their servers at least to get past the portal. I dropped 10.146.24.2 into the settings and boom captive portal!