PAVPN Issue

Hi there, I'm having this issue since upgrading to IOS8.0.2 (with previous 7.x Apple versions we had no issues). We have PAVPN working from mobile devices using F5 edge client to our intranet sites. (The F5/APM config is set up for SSO for our sharepoint sites). When i enter the URL of the internal service into the Sarafi browser, after about 1 second i get the error message that the page cannot be displayed as the server is not responding. If i then refresh the page, the client connects and the page loads successfully. This happens every time for some users. For others it is intermittent. Has anyone encountered this issue as yet with IOS8? We are running 11.5.0 on the F5. I get the same issue on IPhone/IPAD and various models of them. Thanks, Andy