I have the same problem at the same version. I use Ipad-mini-2 os 9.3.5, iphone6 iphone7 ios 10.3.1 and Pulse Mobile 6.3.172163 that error with "Connection Error" and "The server is not responding". If remove the pulse mobile and reinstall again. The first time connect to the PSA, the login page appear. After disconnect and connect aggin."Connection Error" and "The server is not responding" appear again, no more the login page appear. But all of android smart phones that I test is always working normally.