Captive portal flow Android 11

Question

With the update to Android 11 this wonderful captive portal solution stopped working: https://github.com/ConnectBox/simple-offline-captive-portal

The problem is that on my Pixel3 with Android 11 the captive portal page will not close after clicking the OK button. It just remains open and the wifi is not accepted.

After looking into the requests I am really lost why that happens as I do not see any difference between Android 10 and Android 11:

Android 10

"POST /generate_204 HTTP/1.1" 200 7520 "http://connectivitycheck.gstatic.com/generate_204" "Mozilla/5.0 (Linux; Android 10; Pixel 3 Build/QP1A.190711.020.C3; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/78.0.3904.90 Mobile Safari/537.36"
"GET /generate_204 HTTP/1.1" 204 0 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.32 Safari/537.36"
...(several GET requests) ...
"GET /generate_204 HTTP/1.1" 204 0 "-" "Dalvik/2.1.0 (Linux; U; Android 10; Pixel 3 Build/QP1A.190711.020.C3)"
....

Android 11

"POST /generate_204 HTTP/1.1" 200 7584 "http://connectivitycheck.gstatic.com/generate_204" "Mozilla/5.0 (Linux; Android 11; Pixel 3 Build/RP1A.201005.004; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/86.0.4240.75 Mobile Safari/537.36"
"GET /generate_204 HTTP/1.1" 204 0 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.32 Safari/537.36"
"GET /gen_204 HTTP/1.1" 204 0 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.32 Safari/537.36"

Android 10 works like a charm - Android 11 stopped working after the OK button.

Any help - experience how to get captive portals with Android 11 working - ideas how to debug this are welcome. I already tried logging HTTP and DNS traffic on the raspberry the captive portal is running on but nothing that seems to be leading to that error.

Answer 1

I think the Problem is the App Android System WebView.

For me it was needed to update after the Systemupdate, because there were many Apps which crashed, including the Captive Portal.