We have issues with Android and iOS devices when trying to connect to a web service running on IIS 10 (Windows 2016 server) where the server is set to accept a client certificate if provided.
On iOS before the connection gets into the handshaking phase where the client certificate is requested, the HTTP connection hangs (and on iOS 10 will start using up large amounts of memory).
On Android we get back error HTTP_1_1_REQUIRED .
By default IIS 10 uses HTTP/2 and iOS and Android devices seems to have problems with HTTP/2 (not yet confirmed).
Steps to reproduce:
1. Set up IIS 10 web server running on unmodified Windows 2016 Server
2. Configure website to use SSL and "Accept" client certificate
3. Try to connect to website from Safari on iOS
Request hangs for a looong time or fails with timout error.
As a workaround we found the way to disable HTTP/2 in IIS 10 by setting the registry value
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters\EnableHttp2Tls
(REG_DWORD) to 0. However this is for the whole IIS server (all hosted WEB sites) and this requires a Windows system restart.
Our question is: how to disable HTTP/2 for a web site not only (something in web.config or similar).
Dorel Sturm
