The mobile client should work better without Java on it, because the idea was that it would use HTML5 and AJAX to connect through a local WiFi connection. If the client has both IOS and a Java system on their tablet/phone, they may get different results with the cellular connection turned off and the Java system temporarily defeated ( reboot usually required ) from the PLC locale than away at home. The use of ‘Authentication’ ( as in OAuth /OpenID or ‘Secure ID’, SAML etc. ) was supposed to take place in Ignition 8, yet TLS and SSL may have been changed earlier- that would be around 7.9.10. I made some posts earlier about my own problems with Login when AT&T decided that users must ‘Authenticate’ for their mail system. If this was done, or the IOS version updated- it might explain the login failure. That is why you might try Inductive Automation support section through e-mail. The website is ( drumroll )
https://support.inductiveautomation.com then check policies- your organization may have priority e-mail support. They may or may not find it easier to start with this thread. Use triple marks in your mail using the character above the tab ( usually the same key as the curvy tilde to the left of the number 1 ) to avoid immediate use of the link. That could also be cut and pasted from
http://forum.inductiveautomation.com/t/java-error-with-mobile-ignition/27825/4 yet they might need to logon to the forum and open a word-processor program to capture what has been said.
Much of it is at
file:///C:/Users/jlivingston/Desktop/IgnitionTrng/Ign79Man/DOC79/About-Mobile-Clients_6046597.html on my machine- your path to a downloaded 7.9 manual would be similar.