This is exactly why I keep an older laptop running Mac OS El Capitan with the old, desktop GMATPrep software v 2.5 still installed (and working great, I might add).
Once the software is installed, there is no need to worry about what's going on with GMAC's servers, or even having an internet connection, in order to access Exams 1-6. The 6 exams and Question Pack 1 never expire, and I can reset the exams as many times as I want.
Of course, this only still works for me because I bought these products many years ago and activated them on the actual machine I'm still using. For most students having trouble with GMAT Official Prep, this "desktop software workaround" method will only allow you access to free Exams 1 and 2, but it's useful nonetheless.
https://gmatclub.com/forum/how-to-downl ... 75394.html