Samsung devices don't receive a pop-up

[Bwansen]

I am having trouble connecting Samsung phones to the captive portal. They never receive a pop-up with the website, the wifi connection is just marked as not having Internet connection. You can only get to the website if you dig through the menu and find the "Manage router" option for the wifi.
Other Android devices worked fine so far, same for Apple and Windows devices of all kinds I tried. Only Samsung seems to use a different mechanism for detecting captive portals other than the regular Android mechanism - which is pretty annoying because where I live, about one third of all smartphones are Samsung devices.

I already did some Internet search myself yet can't seem to find a proper solution - there was a hint towards Samsung phones probing port 5094 on a certain IP (not mentioning which IP), and several "solutions" like changing the IP address of the AP to a public one or changing the http reply code that's generated when generate_204 is being requested to something else, all of which breaks the captive portal for other devices. So, I currently have no clue of how to fix it myself.

[CodyTolene]

@Bwansen Very interesting I will try to dig into this soon and follow up, hopefully with a solution. Thank you I appreciate your detailed report

[CodyTolene]

There is one thing I would like to try. That would be to update this line from:

return redirect(f"http://{self.domain}/", 302)

to

return redirect(f"http://{self.domain}/", 200)

The 200 response code may work for your version of Android + Samsung in this case.