Mobile device is not able to connect network if the Symantec Endpoint protection (SEP) SRP [VPN] is set to default VPN and there are multiple On-demand VPNs in network.
SEP mobile app installed on a Mobile with VPN enabled and the environment has multiple on-demand VPNs
As of now, SEP Mobile app does not support multiple On-Demand VPNs
Configure the organization defined VPN as Default, do not use the SEP SRP [VPN]
There is nothing much SEP Mobile can do to set the default VPN. You may be able to use the MDM policy to set the default VPN.