I’ve updated my lab environment with Citrix Gateway push OTP support and had some trouble in configuring the Citrix SSO app on my iPhone. For some reason it couldn’t setup the gateway connection and it wasn’t reachable. (Well that was my bad in checking all my devices but I’ll get to that)
Before the push OTP change I’ve worked with the authenticator app behavior and put in the code myself and this worked fine. The change to push OTP isn’t too difficult, and the following articles give you plenty of how-to information:
Keep in mind that if you have setup a previous OTP setup like I had the encryption part needs to be migrated otherwise it just won’t work. Registration cannot complete if you just flip it on and be done with it. Follow the migration part or just start fresh with OTP encryption enabled by default.
After I corrected the encryption problem I still could not register through the Citrix SSO app for push OTP functionality. It kept giving me the error gateway not reachable, fully checked everything in my environment was up and working. It kept me puzzling that it works fine with the previous authenticator method and if I re-registered it that way it would work (without the push of course because that functionality sits in the Citrix SSO app)
Finally after more troubleshooting I found the problem… because I’ve upgraded and integrated ADFS 2019 in my environment my content switching server and gateway etc. also needed to be SNI aware. Remember that everything worked fine on my Windows devices (even the Citrix SSO VPN functionality which I use quite often) but just not on my iPhone. Turning off SNI was the solution, it seems that the Citrix SSO app on iOS doesn’t support SNI.
Hope it helps!