Ran into some fun with setting up FAS for MFA. I was testing a shorter list of ciphers on a test SSL profile on ADC on the test vServer. Come to find out, when accessing a machine that was using MFA from outside the network, I was getting an SSL error 4 on Windows machines and SSL error 47 on Stratodesk machines. I hadn’t seen that error since Receiver 4.x. It appears there are some additional ciphers needed in regards to the Citrix Workspace App. It appeared to work fine with the other cipher set using the HTML5 Workspace App. This article has the updated cipher set you need to have or it may cause you some issues (Changes To FAS Ciphers). These would be applied to your SSL profile assigned to the vServer on the ADC.
I also ran into an issue with EndGame.
When trying to connect from to VDI Windows 10 machines, you would encounter an incorrect user name or password error if EndGame was enabled, instead of it SSO logging you in.
Checking the event log on the machine, you encounter a Smart Card Logon Event 5.
There are 2 DLLs you have to add to a global exclusion, scardhook.dll and scardhook64.dll. These are located under C:\Program Files\Citrix\ICAService. Just excluding those DLLs got rid of the Event 5 Smart Card Logon error and allowed the Provider DLL to initialize.
After getting these exclusions applied, SSO works normally for accessing the VDI machines.