Establish a sonicwall vpn connection using an iOS device and an Apple Time Capsule connected to a cable modem

I am having difficulty establishing a Sonicwall VPN connection to my office using either my iPad or iMac connected wirelessly to an Apple Airport Time Capsule which is connected to a cable modem (non-router). I had been able to establish the connection 9 mos ago. I can establish the VPN connection using a non-iOS device using the same connection above. In addition I can place the iPad and iMac on a different network an establish the VPN connection without any issues. It seems my Apple Airport has an issue with VPN connections with iOS devices. I have no other internet issues using this connection and have made sure all devices are using the most recent firmware.