SSL VPN access behind "dual stack lite" router
I have a sonicwall TZ350. Up to recently my ISP provided me a dynamic IPV4 address. I connected to the SSL VPN via "sonic wall mobile connect" and dyndns. My ISP now changed to dual stack lite. As a result, I cannot connect to the SSL VPN from my mobile anymore. How do I set up the TZ350 to be able to connect to SSL VPN again?
Unfortunately, I'm not an IT professional and have only basic knowledge of networking. Thanks in advance for any help!