Not seen this using inbuild certs, as we use public certs where ever possible (Go Daddy UCC etc), but we did get this issue on containers.
If the issue is the new reqs of iOS13/Androijd Q, then it is only certs generated after 01/07/2019 and that are more than 850 ish days until expiry. everything else is OK with the cert.
11.0.4 had an issue and created certs with a lifespan of 2500+ days, but the iOS and Android only don't like this if it was made after 01/07/2019. I guess this is to allow backward compatibility and give people time to change thier cert.
For the containers we saw the issue, we upgraded to 11.0.5 and then had to get Avaya to regenerate the certs for us, as we cannot.
So if you are using inbuilt certs, make sure you are on 11.0.4.1 and regenerate your cert. Or buy a UCC for your FQDN. Hopefully, you will be fine after this.
IF its none of the above cert problem you have, then I think the VPN connection is probably the issue. Look into getting an SBC to make life simpler (but more expensive!!). If you have SIP Tranformations on your Sonicwall, this will cause problmes, even though you are using a VPN. Seen this issue before.
Jamie Green
[bold]A[/bold]vaya [bold]R[/bold]egistered [bold]S[/bold]pecialist [bold]E[/bold]ngineer