SSL VPN iOS 12 connection error

When there is a port translation from xxxxx to yyyyy before the F5, it will always fail on the iOS12, as this will choose the port configured on the VirtualServer(yyyyy) and not the port chosen to connect to(xxxxx).

Therefor, you have 2 options: 1- keep it simple and keep the destination port and the virtualserver port THE SAME! 2- define a variable on the APM policy such that the iOS will use to connect to.

apm policy agent variable-assign /Common/variable_assign_port-pat {
   variables {
       {
           expression "return {xxxxx}" <--- (!)
           varname session.server.network.port
       }